Lord Stark and his daughters arrive at King’s Landing to discover the intrigues of the king’s realm.
While Bran recovers from his fall, Ned takes only his daughters to Kings Landing. Jon Snow goes with his uncle Benjen to The Wall. Tyrion joins them.
Jon Arryn, the Hand of the King, is dead. King Robert Baratheon plans to ask his oldest friend, Eddard Stark, to take Jon’s place. Across the sea, Viserys Targaryen plans to wed his sister to a nomadic warlord in exchange for an army.
Wells presents Barry with a life-changing choice. Dr. Martin Stein and Ronnie Raymond return to help the S.T.A.R. Labs team with this final fight.
When Harrison activates the particle accelerator, the team has no choice but to evacuate the five metahuman prisoners. Unfortunately, with time running out, Barry has no choice but to turn to Captain Cold for help. Meanwhile, Eddie escapes but has some surprising news for Iris.
While Barry tries to find Eddie, a mysterious mind-controlled thief launches attacks on Central City’s gold reserves. The team soon discovers that a telepathic gorilla is behind the robberies… and is following Harrison’s commands. Meanwhile, Iris confronts Barry, while Harrison prepares to return home.
Barry, Caitlin, Cisco and Joe set a trap for Wells. Cisco uses himself as prey which puts him in grave danger. Meanwhile, Eddie makes a decision regarding Iris, which leaves Joe a bit unsettled.
Joe and Cisco go to Starling City to ask Quentin Lance for his help investigating the site of Harrison’s car accident 15 years ago and determining what really happened. Meanwhile, Eddie is framed for a shooting by a shapeshifing metahuman who can take on the appearance of anyone he touches.
Felicity and Ray Palmer pay a visit to S.T.A.R. Labs for help getting Ray’s ATOM suit to work, and ask Cisco for help. Meanwhile, a young tech expert raises havoc with her insect drones, and Barry asks Ray for help dealing with her.
When a villain calling himself the Trickster runs rampant in Central City, Joe and Barry go to Iron Heights to talk with the original Trickster.
The Flash learns that Captain Cold and Heat Wave have returned to Central City. This time Snart has brought along his baby sister Lisa to help wreak havoc on the city.
Mark Mardon, having survived his apparent death during the black-matter explosion, returns seeking revenge on Joe for the death of his brother Clyde… and has the same weather-manipulation powers as his deceased sibling.
Martin and Ronnie are separated, only to realize that they must learn how to rejoin before Eiling hunts them down and kills them… and the Flash. Meanwhile, Joe shows Barry the 3D images from the Nora Allen crime scene, and Barry asks Martin for advice on time travel.
While Barry, Harrison, and Caitlin hunt down Ronnie, who has attacked a man, Joe recruits Cisco to help him learn the truth about who murdered Nora Allen.
Caitlin takes Barry out to a local karaoke bar to help them both find new loves. Caitlin strikes out but Barry meets a sports reporter and asks her out for a date. Meanwhile, Cisco considers Hartley’s dangerous offer; and the team search for Shawna, a meta-human with teleportation powers who just busted her boyfriend out of Iron Heights.
Dr. Wells’ former protégé, Hartley Rathaway, returns to seek revenge on his mentor. Meanwhile, Iris is hired as a cub reporter; Cisco recalls his first day on the job at S.T.A.R. Labs; and Joe asks Eddie for a favor but asks him to keep it a secret from Barry.
While Barry strives to become fast enough to defeat Reverse-Flash, Captain Cold returns to Central City with a partner and takes Caitlin hostage to force a confrontation with the Flash.
Barry enjoys the annual tradition of tree trimming and gift exchange with Joe and Iris. He gives Iris a touching gift, but the moment is interrupted by Eddie’s arrival.
Barry is thrilled when Oliver, Felicity and Diggle come to Central City to investigate a case involving a deadly boomerang.
The Flash goes up against Farooq aka Blackout, a metahuman who can harness electricity.