Till Death Do Us Part, is the twenty-fourth episode and final episode of Season Nine of NCIS, and the 210th of the series as a whole. This episode also marks the final appearance of both Samantha Ryan and Jonathan Cole respectively and is also the final episode to have Brian Dietzen (James Palmer) credited as Also Starring, a credit he has held since the Season premiere episode, Last Man Standing (episode).
After learning of Vance's abduction, the team continue their full-scale manhunt for terrorist mastermind Harper Dearing who is seeking revenge against the Navy for his son's death. However, Dearing's final game plan involves launching a personal attack with both NCIS and the Navy Yard as the targets and when it finally occurs, the bombing threatens the lives of NCIS and its personnel including those of Gibbs and his team....
The team discover that Vance is safe and unharmed.
It's soon discovered that Dearing is also targeting and killing the people involved in the case concerning a prank which Dearing's son, Evan had a part in.
After her ex-husband is released, Samantha Ryan is forced to go into hiding with her son, Parker and stop participating in the case altogether.
The team bring in Jonathan Cole to help them in the case concerning Dearing and offer him a reduced sentence in exchange for Cole's co-operation in a sting operation.
The team soon realize that Vance's car which is sitting in front of the Navy Yard is rigged to explode and as such, the Navy Yard is evacuated.
While the evacuation takes place, Cole attempts to defuse the bomb in the car but dies when the cell-phone attached to the bomb rings, triggering the bomb.
The force of the explosion leaves the Navy Yard heavily damaged with an unknown number of fatalities and victims.
Jimmy decides to elope with Breena.
Gibbs and Abby are in the lab with Gibbs shielding Abby from the blast just as the bomb hits.
In the squad-room, McGee and many other people who hadn't left the room yet all of them fall to the ground just as the sheer force of the explosion damages the window and presumably knocks the power out which in turns affects the elevator that Tony and Ziva are in, leaving the two of them trapped.
Ducky suffers a heart attack after learning of the attack and collapses on a beach in Miami.