Chuck and Sarah investigate when they suspect that Casey is carrying out private missions. Meanwhile, Chuck fears that the CIA's seemingly perfect new operatives will render him obsolete. Elsewhere, Morgan settles in with a new roommate, and Awesome panics when Ellie embarks on a potentially dangerous line of research.

Bad day gets worse when Sarah throws Chuck a surprising relationship curveball as the CIA orders Vivian Volkoff assassinated. In order to prove Vivian's innocence, Chuck must put his trust in a dangerous ally her father Alexei Volkoff. Meanwhile, Ellie suspects that her mother is interfering with the search into her father's past.