The Suicide Squad is about a team of super-villains do black-ops missions for the government in exchange for lighter sentences. It brings back several characters, including Margot Robbie's Harley Quinn and Viola Davis' Amanda Waller, and adds a slew more, played by people like John Cena and Idris Elba. The tone is a lot jokier, the violence more visceral — literally — and the stakes are higher, thanks to a giant alien starfish bent on world domination.