As Castle and Alexis travel to London, their routine flight turns deadly when the plane’s Air Marshal is found murdered. With the help of Beckett on the ground, Castle and Alexis race against time to find the killer before he carries out his fateful plan.
Alicia faces an uncertain future when she is forced to resign as State’s Attorney in the wake of a voter fraud scandal. Also, R.D. hires Diane and Cary to argue against two ultra-conservative lawyers for a test case involving mandatory minimum sentencing.
In Braavos, Arya sees the Many-Faced God; In King’s Landing, Queen Margaery enjoys her new husband; Tyrion and Varys walk the Long Bridge of Volantis.
Castor pursues the Leda clones for original tissue samples. Helena, who is pregnant and imprisoned, is examined by a mysterious new villain. The Castor boys are also out to play, toying with a frightened young woman, Patty, in a sexy switcheroo that ultimately sets Sarah – and Art – hot on the Castor trail. But it’s not all fun and games for the Castor boys, as Sarah gleans they may have a mysterious defect that puts their lives in peril.
Jay agrees to sub in on Cam’s bowling team, not knowing it’s an all-gay league. Phil and Clair have an unexpectedly nice time with their neighbors. Gloria and Mitch agree to go out with Haley.
When Frankie’s uncle contacts her dad hoping to make amends, Frankie and Mike are caught in the middle of their feud; Sue turns to Axl for advice when she is sent to detention for the first time.
Ra’s al Ghul finally makes Oliver an offer he can’t refuse. The team joins Oliver on his journey to Nanda Parbat where a heartbroken Felicity decides to take matters into her own hands.
A dangerous new alliance is formed as Coulson and Hunter turn to the last person anyone would expect – Grant Ward! As the war between S.H.I.E.L.D. factions continues, Skye and Lincoln will find themselves drawn into this conflict.
Joe and Cisco head to Starling City to continue their investigation of Dr. Wells. While in town, the duo enlists the help of Captain Lance, and Cisco meets the Black Canary, who asks him for a favor. Meanwhile, back in Central City, Barry races to catch a meta-human named Hannibal Bates who can transform himself into every person he touches – which includes Eddie, Iris, Caitlin and even The Flash.
A former boyfriend lures Britta into joining Honda’s guerilla marketing campaign. Jeff looks to get Elroy to like him.