As they seek to uncover the truth behind her father's death, Novak sends his enforces after them and his son later kidnaps Delfina in order to force her mother's hand.
A series of deadly explosions strike oil derricks, and 20 Squad begin hunting down an activist turned terrorist.
Annie begins to suspect the lover's ex-wife for the murder because she inadvertently revealed knowing where the victim was dumped.
They apprehend one of his accomplices before he can release nerve gas in a federal building, where they discover both he and Reid felt betrayed over loved ones left behind during the evacuation from Afghanistan and are seeking retribution.
20 and 60 Squads soon find themselves combating Reid and deactivating the remaining five nerve gas canisters on board the Queen Mary before it's too late.
Chris and Street officially become a couple and the team marks her departure, while Hondo learns that Nichelle is pregnant.