"Supergirl (aka Kara Danvers) has been running across average citizens performing amazing feats all over National City. But that's not even the weirdest thing going on. The Department of Extranormal Operations has captured a mysterious humanoid sea creature. Supergirl must find out what has drawn him to National City, and his connection to this surge of super-citizens"--

While the Flash and Team Arrow closed the dimensional rift looming over Central City, they still have plenty of chaos to deal with: Cisco and Curtis are lost in time, thousands of speedster refugees are now stuck on their earth, and a mad bomber is at large. But when Anti-Matter Man arrives on Supergirl's doorstep on her home of Earth-38, it'll be all hands on deck for a team-up of epic proportions to stop him.