In the hopes of sparing a family further tragedy, the Secretary of the Navy calls on NCIS to help a sailor battling leukemia locate a bone marrow transplant after his two Marine siblings are killed in the line of duty. Also, Bishop returns home to Oklahoma for the Thanksgiving holiday.

After the passengers and crew of a private plane traveling from New Orleans to Washington D.C. are lethally poisoned, all evidence points to the missing chef, Abby's brother, Luca. Gibbs and the D.C. team work in conjunction with Pride and the New Orleans team to locate Luca and determine why a private tech company was targeted, on the first part of a special two-hour crossover event