The team investigates a ransomware attack that takes out the entire power grid for west L.A. and paralyzes the city. Also, as the first holiday season since the death of Sam's wife approaches, he struggles to find the best way for his family to celebrate.

While Hetty is being tortured by her captors in Vietnam, Eric and Nell find a clue to her whereabouts, prompting the team to organize a rescue mission with very little information.