A murder investigation launches Castle into what seems to be an alternate universe where he’s never met Kate Beckett. Castle has to convince Beckett, Esposito and Ryan — now complete strangers — to let him participate in their investigation so he can find his way back to his own world. This inspires Castle & Beckett to finally take a trip to the altar.
Alicia takes on a college rape case which pits her against Louis when it moves from a university hearing to civil court. Eli and Elfman conduct a political focus group. Alicia dives into her campaign for State’s Attorney.
Lockhart arrives. Carrie’s investigation gets complicated.
Peter brings Rebecca in to help locate Neal, who is being held captive by one of her former associates. Jim has lofty aspirations of joining an exclusive group of thieves, and his entry ticket is the diamond currently held by the FBI.
When Clarke discovers a horrifying project being carried out in Mount Weather’s medical ward, she joins forces with an unlikely ally. After Abby confesses to committing a crime, Kane issues an order to have her brutally punished. Meanwhile, Monty warns a distracted Jasper that Clarke could be in trouble, and Octavia continues to fight for Lincoln.
When a cyber attack brings Starling City to its knees, Oliver and Felicity are pushed to their limits to contain the destruction. Life gets even more complicated for Felicity when her mother, Donna, stops by for a surprise visit. Meanwhile, Ted Grant questions Laurel’s motives, and Thea buys an apartment with Malcolm’s “estate” money, which infuriates Oliver.
Eliza and Henry spend the weekend at the Saperstein’s estate but with zero cell reception and a prospective promotion being dangled in front of them, both Henry and Eliza exhibit some questionable behavior.
Eliza observes Henry’s constant bad mood and lack of skills with women and becomes determined to get him some action, whether he wants it or not.
Carrie puts her operation in motion, staging an attack on herself and Ayaan.
While preparing his case against Cary, Finn discovers a potentially devastating piece of evidence which could have ramifications for Alicia and Peter. Eli becomes wary when a new prospective candidate emerges in the race for State’s Attorney.