While on vacation with his friends, a teenager while swimming finds the body of a young Naval Seaman wearing dress whites as well an officer's ceremonial sword and chains around his waist. The NCIS team then head to the USS Foster to investigate and during the investigation, discover some disturbing secrets about the victim as well as evidence of a potential and devastating biological attack against the Foster that puts the lives of its crew and also those of the NCIS team in grave danger...
Four teenagers are on a boat somewhere in the Bahamas.
One of the guys, Brad (The Immortals) then attempts to go swimming, only for his friends, Kyle, Lisa and Ricki to urge him against it given the warnings concerning mako sharks that have been spotted in the area.
Unsurprisingly, Brad ignores the warning, saying that the odds of a shark attack are ten-thousand to one and proceeds to go into the ocean as the others look on in dismay.
As he swims down to the depths of the ocean, everything looks peaceful but Brad then gets the shock of his life when he sees the body of a young sailor.
This causes Brad to abandon his swimming and head back up to the surface to presumably inform his friends of the discovery.
It then cuts to MacDonald where it's shown that he has chains around his waist, chains that are binding him to the seafloor.
In the squad-room, NCIS Special Agent Leroy Jethro Gibbs is telling agents Anthony DiNozzo and Caitlin Todd that the body has been shipped to NCIS with the ID matching that of Seaman Russell MacDonald, a nineteen year old man assigned to the USS Foster.
Kate then remarks that the Foster is a Destroyer, spruance class with Gibbs giving her rare praise on it.
Gibbs remarks that two days previously, the Foster had just left Roosevelt Roads Naval Station in Puerto Rico and was heading for Norfolk while MacDonald's body was found somewhere in the Bahamas.
Tony then begins rambling on about how he loves Puerto Rico despite never being there much to the amusement of Gibbs and Kate.
In Autopsy, Donald Mallard is studying MacDonald's body and remarks that the "ceremonial" sword MacDonald has shouldn't be in his possession with the blade sharp enough to cut someone's throat.
Eventually, having gotten nothing yet, the team leave Autopsy so that Ducky can get to work.
As they head for the lift, Gibbs orders Kate and Tony to talk to MacDonald's mother but the two debate that the other should go in their place, causing Gibbs to remark, "When did an order turn into a debate?".
Tony braces himself for an interview. Kate advises him to take a breath and think of Puerto Rico. They eventually get to talk to Mrs. MacDonald who tells them that her husband, Russell's father who was Scottish and a member of the Black Watch died when Russell was twelve years old.
She tells them that her son had a lot of friends on board the ship and that he was very friendly before insisting that there's no way her son could have killed himself as the MacDonalds are Catholic and in the Catholic culture, suicide is a mortal sin.
Outside the MacDonald's house, Kate is upset, stating she didn't know how bad the interview was going to be.
Tony tells he didn't because he always had someone else interviewing the victim's family.
When she starts rambling on, Tony urges her to breathe.
A while later, the team soon get out to the U.S.S. Foster.
After Morris and Robbins have left, Kate expresses doubts over the hospitality.
Gibbs assures her she'll get over it, stating that NCIS is like the Internal Affairs of the Navy and that the only thing the people on board ships can do is stonewall or kiss ass.
When Kate is shocked to learn that they're going to sleeping in the same room together, Gibbs impatiently insists he'll take the couch and then heads off to the bunk where MacDonald was.
On the way, he meets Petty Officer Carnahan who states that he didn't know MacDonald and that the other guy kept to himself.
DiNozzo talks to Reynolds (The Immortals) and despite having spent a year at a high school, was good at his occupation but had displayed some signs recently, showing that he seemed to be incapable of focusing on the job at hand.
Kate gets the Medical Corpsman who tells her that MacDonald was having a hard time adjusting to ship life and she even recommended he get into counseling to help him.
She also mentions that MacDonald was obsessed with a mysterious friend of his and when Kate presses her further, admits that she doesn't think MacDonald would be the one to kill himself.
Out on board the deck, amid the loud engines, the team compare notes.
Gibbs shows Tony and Kate regarding Japanese sword fighting and tells them that MacDonald was teaching himself how to use the sword they found with him.
It then cuts to Gibbs who's staring at the book while Kate and Tony look at Gibbs.
The team return to their sleeping quarters and via the laptop, hold a conference with Abigail Sciuto who tells that she has a St. Christopher medal that MacDonald was wearing around his neck.
She also shows them a character sheet which she believes is for an MMORPG (short for Massive multi-player online role playing game) that in her own words is "huge on the Internet".
When Gibbs asks where the evidence is, Kate believes that if anything exists, then it's going to be on the Internet rather than on MacDonald's computer.
She also remarks to Abby that MacDonald's file didn't show anything regarding foreign language skills and as such, Abby is probably looking for something in English.
Abby finds that the sword came into contact with hard metal and as Kate goes off, armed with that lead, Gibbs and Tony go to talk to Ducky next.
Once the morgue has been brought online, Tony expresses disgust at Ducky and his Pathology Assistant working on the body while teleconferencing.
Ducky reveals that there's evidence strongly suggesting that MacDonald drowned and that he was also alive when he went into the sea.
Tony talks to Ensign Ray in regards to the sword they found on MacDonald's body.
Ray confirms that all the thirty-two swords including his are accounted for with the topic then turning to where MacDonald got the sword.
Ray tells him there's only place which Tony figures out is Roosevelt Roads Naval Station in Puerto Rico.
Gibbs interviews Commander Rivers about the sword and Rivers tell him that an ideal place for a sword fight to be held is damage control, in the machine shop at night-time.
Back at NCIS, Abby's busy playing the MMORPG on her computer and she's already starting to get the hang of it.
Ducky who's passing the lab hears her shouting and comes in to see what she's doing. He starts telling her it reminds her of something but he comes up blank, causing Abby to chuckle.
On the Foster, the Corpsman is busy going through the record she's gotten for Kate and there's nothing suggesting any suspicious injuries.
Kate recommends she go get some records regarding some questionable injuries and the Corpsman agrees, stating she'll need a few hours to get them.
Ducky brings a Caf-Pow to Abby for which she calls him a "prince".
It's revealed that the game Abby's playing is called "The Immortals" and she tells Ducky that if she can get into the dungeon stronghold, then she can get a log of everyone who's played the game.
Unfortunately, she gets distracted and her game character is killed by an Orc, forcing her to begin again.
Back on the ship, Gibbs gets a call from Abby who tells him she's obtained the server logs and has confirmed without a doubt that MacDonald played the game as a character Weylin, whose main rival had a character called Kinvaras. She also states that their main mode of combat was sword fighting and she has a big whoop for him.
"Fine, whoop me", Gibbs says.
Abby then announces that the guy who plays Kinvaras logs on from the Foster, the same ship that Gibbs and the team are on at the moment.
It then cuts Gibbs who hangs up his phone, frustrated and annoyed at the turn of events while Tony just looks at Gibbs.
To catch some air, Gibbs heads onto the side of the ship and he and Tony discuss the game before they head back inside.
Once inside, Tony recommends he go to Puerto Rico, buy a sword undercover, bust the clerk and then trade the bust in exchange for information on who else bought a sword.
Tony wants twenty-four hours while Gibbs suggests six.
Tony tries going for twelve but a look from Gibbs has Tony agreeing to the six hour deadline.
It then shows a Navy copter departing the ship's helipad.
Back in her lab, amid empty cups of Caf-Pow, Abby gets to the online journal that MacDonald's alter-ego, Waylin used. She tries to access it but unfortunately, it's password-protected.
However, Abby has a secret weapon: the program, Codebreaker which is capable of cracking any password. She presses a key and the program gets to work, going through the numerous passwords.
Abby leans back in her chair, stating to no-one in earshot that this (cracking the password) is going to take a while.
Tony has arrived in Puerto Rico and posing as a Naval officer, begins trying on sunglasses. He tries to bride the Exchange Clerk and when that doesn't work, states that he's an NCIS Special Agent.
The Clerk freaks out and begins swearing at him in Spanish while throwing random clothes at him including a pair of socks, all while Tony tries to calm her down.
Gibbs and Kate are processing the machine shop's metal poles where there are some marks on them which might have been cased by the sword.
When Gibbs confronts her about the possibility of personal feelings coloring her judgment, Kate states it isn't but also tells Gibbs that he hired her because of her knowledge and experience.
Gibbs's cell-phone rings.
It's Tony who has some news for him.
Gibbs heads up onto the deck to get a better reception and Tony tells him that MacDonald and three other seamen illegally bought swords and Tony has their descriptions.
In an office, Gibbs and Kate are going through countless files, trying to find a match to a sword buyer with suspicious injuries.
After much searching, Kate finally discovers a possible suspect: Petty Officer Ronald Zuger who cut his arm on a plate glass window but Kate notices that there were no glass shards of any kind in the wound.
They corner Zuger playing the Immortals in the Computer Center, confirming that he is indeed Kinvaras and Gibbs drags him in for interrogation.
Meanwhile, Abby's gotten into Weylin's diary and rings Gibbs's cell-phone but gets Kate instead. She tells Kate that MacDonald had diarrhea of the keyboard and that going through the diary will take a while.
Kate volunteers to do it in her place.
Back at the interrogation, Gibbs talks to Zuger in regards to the game but Zuger has an alibi: he was helping someone with a computer problem the night MacDonald went overboard.
"Big problem", Gibbs states.
"Huge, sir", Zuger replies.
Kate is going through MacDonald's diary and finds disturbing evidence that suggests that MacDonald was a nut job.
It then ends with MacDonald's voice stating that the element of surprise will be a great advantage for MacDonald's final triumph.
It then cuts to Kate who looks deeply concerned at those words.
Now Gibbs is busy interrogating Petty Officer Carnahan who is Zuger's alibi. He tells Gibbs that he's been downloading a lot of "stuff" aka porn onto his laptop and knowing that his C.O was suspicious, Carnahan had Zuger clean out the hard-drive.
The team are now talking to Ducky who tells them that MacDonald wasn't in a struggle before he went into the sea and Ducky also believes that "the afterlife might be an improvement for a young man so troubled".
After Ducky signs off, Gibbs and Tony are coming to the conclusion that MacDonald's death is suicide given that one suspect, Zuger has an iron-clad alibi. Kate doesn't buy it for a second, stating that there's more to it.
While Gibbs believes it's the Catholic religion, Kate insists it's the diary and that she's on the last entry.
Gibbs request Zuger's records which Tony does so and while on hold, asks Gibbs if he's interesting in seeing what Tony brought back from Puerto Rico.
Gibbs refuses and then talks to Kate who tells them that MacDonald had planned to flee the ship and also "release a great plague against the realm as the sun sets beneath the next full moon".
Kate thinks that the realm is the Foster as MacDonald had grown convinced that his ship-mates were aiding Kinvaras.
Gibbs then discovers that MacDonald had applied for the Nuclear, Biological and Chemical Weapons program and although MacDonald successfully passed the physical, he'd flunked the psych.
Gibbs realizes that MacDonald's going to set off a bio bomb on board the Foster and isn't impressed when Tony tells him the sun will set an hour from now.
Gibbs barges into a meeting and tells the ship's commander and the personnel in attendance about the bio threat.
As such, the ship's put on high alert and everyone gets into gear to prepare something like this from happening.
Tony has grabbed Zuger and demands he check his site for any clues in regards to the bomb threat.
Kate rings Homeland Security in regards to any missing materials needed for a dirty bomb but they don't think so.
Either way, they're going to check just to be on the safe side.
In the center, Zuger realizes MacDonald has destroyed his site, causing him to break down but Gibbs forces him back to reality.
In the meantime, Tony and Kate are pouring over the diary, looking for something, anything that might help them.
The ship is being checked and evac helicopters are on their way.
An enraged Gibbs confronts Zuger and Zuger tells him that MacDonald had gone insane, believing that he was really Weylin and that Zuger was Kinvaras.
Zuger didn't kill him but he told MacDonald that if he thought he was really immortal, he should be capable of walking across the ocean floor until he got to dry land.
When Gibbs demands to know why, Zuger tells him it was for the sake of winning the game.
When the deadline for the bio bomb approaches, Commander Rivers demands Gibbs come to his lab.
Tony and Kate talk about what MacDonald said about cutting off the head so that the physical body will die.
Kate then realizes it might be a computer virus, not a bio bomb as they thought and MacDonald's paranoia was so strong the threat might even extend to killing the ship's commander.
With that knowledge in hand, the two flee the computer area.
In Rivers's cabin, Rivers himself is busy berating Gibbs for having the ship in such a state.
Tony and Kate then storm in and demand to know where the Commander is at this time every day.
The Commander states he's always here in his cabin.
Which means the bomb isn't on board the ship.
It's in the Commander's office.
Everyone runs for cover just as the sun sets.
And seconds later, the commander's sea cabin blown apart.
In the lab, Abby is trying to explain the whole thing to Ducky but he eventually gives up, stating that sometimes the dead make more sense to him than the living.
Back on the ship, the team are packing their belongings to go home.
Kate is unusually silent and Gibbs asks if she's alright.
Kate states that she can't believe how the line between fantasy and reality was so blurred for MacDonald. Gibbs tells her that for MacDonald, destroying Zuger's website was every bit as real and violent as trying to kill the Skipper.
Tony tells them that he's really glad his parents urged to do him sports when he was in high school.
The two soon allow Tony to give him what he brought for them in Puerto Rico.
Kate gets a Puerto Rican bikini and matching bottoms.
Gibbs asks her if she's going to put it on.
Kate tells him to go first and throws them at him with Gibbs assuring her they won't fit him.
Gibbs has an MMORPG starter kit which happens to be Spanish.
With that, they all leave the room.
Seconds later, though, Tony grabs the bikini bottoms, stuffs them into his pocket and then leaves, closing the door behind him, leaving the room empty.
- Executive Producer Donald P. Bellisario's stepson Chad W. Murray appeared in the role of Seaman Russell MacDonald, the victim. He is also Sean Murray's (Tim McGee) brother with Chad Murray currently serving as a producer on the spin-off series, NCIS: Los Angeles.
|Leroy Jethro Gibbs||Mark Harmon||An NCIS Special Agent in charge of the main NCIS Major Case Response Team.|
|Anthony DiNozzo||Michael Weatherly||The Senior Agent of the main NCIS Major Case Response Team and also the second-in-command.|
|Caitlin Todd||Sasha Alexander||A Secret Service Agent previously assigned to the Presidential Protection Detail on Air Force One and who is now an NCIS Special Agent as well as Tony DiNozzo's partner.|
|Abigail Sciuto||Pauley Perette||A Goth who is also the Chief Forensic Scientist for the NCIS Major Case Response Team.|
|Donald Mallard||David McCallum||NCIS's Chief Medical Examiner.|
|Commander Rivers, USN||Mark Sivertsen||The Commander of the USS Foster.|
|Lieutenant Commander Robbins, USN||David Andriole||Assigned to the USS Foster, he gives up his quarters to the three visiting NCIS Agents: Leroy Jethro Gibbs, Anthony DiNozzo and Kate Todd.|
|Lieutenant Reynolds (The Immortals), USN||Kieran Mulroney||Deceased Seaman Russell MacDonald's C.O.|
|Ensign Ray, USN||Colin Bain||An Ensign who tells Agent DiNozzo about his own handheld sword. This later prompts DiNozzo to go undercover to the Base Exchange in Puerto Rico to get information on the sword.|
|Chief Petty Officer Morris, USN||Eamon Hunt||A Chief Petty Officer who brings the team to their sleeping quarters when the team reach the USS Foster.|
|Petty Officer Ronald Zuger, USN||Julian Bailey||Served on the Foster and is also on the same gaming site as MacDonald. His alter-ego was Kinvaras and as such, the two were fierce rivals.|
|Petty Officer Carnahan, USN||Bradley Snedeker||A Petty Officer who recruited Petty Officer Zuger to help erase porn that was on his hard-drive.|
|Petty Officer Murray, USN||Casey Nelson||Uncredited Role.|
|Seaman Russell MacDonald, USN||Chad W. Murray||The victim.|
|Medical Corpsman, USN||Elizabeth Morehead||Kate interviewed her about Russell MacDonald.|
|Pathology Assistant, NCIS||Adam Vanderwielen||Helps Ducky with the on scene exam.|
|Mrs. MacDonald||Brooks Almy||Mother of the victim.|
|Brad (The Immortals)||Jeff Peterson (actor)||One of the four teenagers. During a swim, he discovers the victim.|
|Kyle||Michael McLafferty||One of the four teenagers on vacation.|
|Lisa||Jeni C. Wilson||One of the four teenagers on vacation.|
|Ricki||Nina Alexander||One of the four teenagers on vacation.|
|Exchange Clerk||Yvonne DeLaRosa||Sold a ceremonial sword to an enlisted serviceman.|