The team searches for a sniper who is terrorizing New York; Beckett tries to hide her worsening PTSD from Castle and the detectives.
The stress of McGee and Delilah's (Margo Harshman) imminent wedding takes its toll, as Delilah is rushed to the hospital. Also, the NCIS team travels out to sea after a young and healthy Petty Officer aboard a Navy destroyer dies in his sleep.
Nancy goes back to California and pursues her custody battle against Jill; Andy's relationship takes a odd turn; Shane tries college; back on Wall Street, Doug makes do without Nancy.
Natalie becomes convinced a critic (Guest Star Dylan Baker) who panned her daughter Julie's theatrical performance was responsible for a murder at the same time as the show.
The team investigates the murder of a Navy contractor involved with selling confidential data.