Chuck and Sarah race against time to take down a dangerous computer virus, pitting them against Robyn Cunnings, a ruthless spy who will stop at nothing to get what she needs. Meanwhile, Ellie and Awesome's date night takes a dangerous turn and Morgan is sent on a special mission to recover Chuck's P.A.N.T.S.

Sarah is forced to confront a secret from her past and feels she must do so alone, while Chuck urges her to let him help. When Sarah encounters her original handler, Kieran Ryker, she fears that he will harm those closest to her, including her mom.