The trailer features the squad being recruited by Amanda Waller (Viola Davis) on a mission to destroy a Nazi-era prison and fighting Starro, a telepathic starfish.
Gunn's version of DC supervillains features some stars from the first film, including Margot Robbie as Harley Quinn, Davis as Waller, Jai Courtney as Captain Boomerang and Joel Kinnaman as Rick Flag.
New faces audiences will see include John Cena as Peacemaker, Idris Elba as Bloodsport, Pete Davidson as Blackguard, Peter Capaldi as Thinker, Alice Braga as Sul Soria, Sean Gunn as Weasel, David Dastmalchian as Polka-Dot Man, Daniela Melchior as Ratcatcher 2, Nathan Fillion as T.D.K., Mayling Ng as Mongal, Michael Rooker as Savant, and Flula Borg as Javelin.
"Suicide Squad" creator John Ostrander appears in the movie as Dr. Fitzgibbon.
"The Suicide Squad" hits theaters on August 6 and will play on HBO Max for 30 days simultaneously. (CNN and HBO Max share parent company WarnerMedia.)