Wanting to enjoy his limited time before the crisis arrives, Barry and Iris decide to go on a beach vacation. Their vacation serves as a test for Cisco to see if he can handle protecting Central City on his own once Barry is gone. He’ll have Frost and Dibney to help, but he’s the one calling the shots. Cisco thinks he’ll be able to handle it thanks to his newly developed A.I.; one modeled after Barry’s decision making history.
It would have gone smoothly if it wasn’t for Breacher’s arrival. One late night when Cisco and Kamila are trying to sleep, he appears with the news of Cynthia’s passing. Breacher has always been someone who takes life extremely serious; he rarely shows emotion, except when it comes to his daughter. Cynthia died while searching for the elusive hacker, Echo. Breacher thinks Cisco would be the best one to find her killer and bring her to justice.
Breacher is right: Cisco is an excellent scientist who has picked up some useful detective skills during the past few years from Barry. He’s not entirely confident in his abilities, though, relying on his A.I. to make all major decisions for him. It takes Kamila’s constant encouragement– and nearly being framed for murder– for it to sink in for Cisco that he’s as capable as Barry to lead the team. Once his confidence is built up, he’s able to find Cynthia’s killer. It’s Echo, a hacker who looks just like Cisco from another Earth. Capturing Echo is a huge ego boost for him, so maybe he’ll be less afraid of a future without Barry.
While Cisco is mostly on his own, Joe confronts Nash on his intentions on their Earth. We know Nash is looking for the Monitor, specifically in the cave he has been hiding out in, but he’s not too keen on opening up to Joe about those details. The confrontation leads to a cave-in, trapping the two together until Dibny comes to the rescue. Joe remains optimistic during the ordeal, much to Nasha’s dismay, who feels he’s foolishly optimistic. It’s typically been Cisco who makes the connection with each new Wells, but he’s busy searching for Cynthia’s killer. Joe, protective of Central City, takes it upon himself to keep an eye on Nash this go around. He isn’t aggressive– he’s vulnerable with Nash to appeal to his humanity. It must work, because Nash drops the biggest news of the season: he can save Barry.