Sandblast is the seventy-seventh episode of NCIS, and the seventh episode in Season Four. This episode also marks the debut appearance of Army CID Lt. Colonel Hollis Mann and Tony's DiNozzo girlfriend, Dr. Jeanne Benoit.
A Marine Colonel dies in an explosion at a military golf course, prompting the NCIS team to investigate with the help of an Army CID team led by Lt. Hollis Mann to find who is responsible. Meanwhile, the victim's son is hellbent on dropping out of college and signing up to the Marines to avenge his father, forcing Tony to try and talk the youngster out of making a big mistake.
Mann says that Army CID did a profile on Gibbs for her. This profile presumably includes information on Gibbs's first marriage and the deaths of his first wife and daughter, since later in the episode Mann mentions Gibbs's four marriages. However, this is inconsistent with the earlier scene in Gibbs's basement, when Gibbs says he has been divorced three times and Mann responds "only three?" and appears not to recognize Kelly's name on Gibbs's boat. Moreover, in the later episode Ex-File (episode), she appears ignorant of Gibbs's first marriage.
This is the second time McGee has been infected with poison ivy, the first being in the Season 2 episode, Caught on Tape (episode).