The CW offered a first look at their "The Flash"/"Arrow" spinoff, "Legends of Tomorrow," with a trailer that shows new and returning heroes in action, including the debuting Hawkgirl (Ciara Renee), the newly renamed White Canary (Caity Lotz) and the Atom (Brandon Routh), who finally unveils his long-awaited shrinking technology.

Scheduled to premiere as part of the network's midseason lineup, the eagerly anticipated "Arrow"/"The Flash" spinoff also stars Wentworth Miller as Leonard Snart/Captain Cold, Dominic Purcell as Mick Rory/Heat Wave, Victor Garber as Professor Martin Stein (one-half of Firestorm) and Arthur Darvill as time-traveler Rip Hunter. Stephen Amell and Grant Gustin briefly appear as Arrow and the Flash in the trailer as well.

Alongside the trailer, the CW also released a behind-the-scenes featuette, which shows the work that went into the action sequences seen in the trailer and offers a few insights from executive producer Marc Guggenheim.

"'Arrow' is all about saving Starling City, 'Flash' is all about saving Central City. This is the first show that we're doing that's all about saving the world," Guggenheim explains. He also confirms that the first season will run for 13 episodes.

Here's the official synopsis for "DC's Legends of Tomorrow":

When heroes alone are not enough... the world needs legends. Having seen the future, one he will desperately try to prevent from happening, time-traveling rogue Rip Hunter is tasked with assembling a disparate group of both heroes and villains to confront an unstoppable threat - one in which not only is the planet at stake, but all of time itself. Can this ragtag team defeat an immortal threat unlike anything they have ever known? DC'S LEGENDS OF TOMORROW stars Victor Garber ("The Flash," "Alias"); Brandon Routh ("Arrow," "Superman Returns"); Arthur Darvill ("Doctor Who"); Caity Lotz ("Arrow"); Ciarra Renee ("Pippin"); Franz Drameh ("Edge of Tomorrow"); with Dominic Purcell ("The Flash," "Prison Break"); and Wentworth Miller ("The Flash," "Prison Break"). Based on the characters from DC Comics, DC'S LEGENDS OF TOMORROW is from Bonanza Productions Inc. in association with Berlanti Productions and Warner Bros. Television, with executive producers Greg Berlanti ("Arrow," "The Flash," upcoming "Pan"), Marc Guggenheim ("Arrow," "Eli Stone," "Percy Jackson: Sea of Monsters"), Andrew Kreisberg ("Arrow," "The Flash," "Eli Stone," "Warehouse 13") and Sarah Schechter ("Arrow," "The Flash," upcoming "Pan").