The Gibbs gang joins Hollis to investigate the death of a Marine captain due to a harpoon through his torso in the study of his home in family housing at Fort Belvoir, Virginia, an Army post. The victim worked under an Army major on an inter-agency task force at the Defense Intelligence Agency (DIA). The NCIS seizes and keeps the victim's laptop computer, but the DIA sends a techie to shadow Abby while she works on it; Abby starts frozen, but she thaws quickly. The team find a network of love interests, including one of Gibbs's exes. Tony and Ziva find a partial print, Abby cracks a song, and McGee cracks a code, which allows the bunch to nab the bad guy and Abby to slug him.