Oliver brings Sara into the Arrow team. Watching Oliver and Diggle spar with Sara and talk old scars, Felicity starts to feel left out. The team is investigating a villain named William Tockman, a.k.a. The Clock King, who is a brilliant thief armed with technology that can open any bank vault in Starling City. After The Clock King infiltrates the computer systems in the lair, Felicity feels pressure to prove her worth. When she gets a lead on Tockman’s whereabouts, she heads out without the team, putting her in peril. Meanwhile, Oliver throws Sara a welcome home party, but Laurel refuses to attend. After Lance makes his case for a family dinner, Laurel acquiesces, but when Oliver shows up with Sara, she loses her temper on both of them.

Frankie tries to persuade Mike to attend a dinner honoring his dedicated service at the quarry; Sue forms a plan to build connections between students; Axl hopes to track down a girl who left a message on his phone.

With their lives in danger in New Vegas, Monroe and Connor face a difficult decision in order to survive. Back in Willoughby, Miles questions whether he can trust Neville and Jason to help take down the Patriots. Meanwhile, Aaron and Priscilla find themselves at odds over the nano code.

When a guilt-ridden young woman confesses to the murder of a struggling actor — knowing details only the killer could know — Beckett and Castle seem to have an open-and-shut case, until they uncover proof that their suspect couldn’t possibly be the killer. When a second person confesses, equally convinced they committed the murder, the team realizes the case is far more mysterious than they thought.

When Barney suffers from the world’s worst hangover the morning of his wedding, the gang tries to figure out the far-fetched ingredients to concoct the Stinson Hangover Fixer Elixir.

While in Bolivia with Riley to protect a presidential candidate from assassination, Gabriel is shocked to learn his best friend is the suspect.

In 2002, Cohle and Hart begin to fall back to familiar and violent obsessions. Hart exacts savage vengeance on a pair of teenage boys, and Cohle becomes convinced they left something undone in 1995. Working on his own, Cohle traces a sinister connection between missing children along the coast and evangelist Billy Lee Tuttle’s Wellsprings Program. Hart is reintroduced to a former prostitute he met during the Lange investigation. In 2012, Papania and Gilbough question Maggie, now divorced from Marty, about Cohle and Hart during 2002, the year their relationship fractured and Cohle quit the force following a suspension.

Marty and Jeannie come up with different approaches on how to deal with Lukas’ attempts to sabotage DollaHyde. Meanwhile, the relationship between Roscoe and Lex becomes a problem for Marty.

The murder of a high school mean girl draws Castle back to one of his many alma maters, where he is giddy to learn that the evidence points to a surprising perpetrator – a teenage telekinetic, throwing he and Beckett into a real-life “Carrie.”

Gabriel and Cybercom investigate when artificial intelligence scientists are infected and killed by microscopic robots.