Deadshot (Will Smith) assassinates a mafia snitch, then goes shopping with his daughter Zoey, when Batman appears and arrests him.
Batman then chases after the Joker (Jared Leto) and Harley Quinn (Margot Robbie) and captures Harley after their car falls into the river and the Joker leaves her behind.
Captain Boomerang (Jai Courtney) is arrested by the Flash (Ezra Miller) while robbing a bank. Killer Croc (Adewale Akinoeye-Agbaje) is captured by the government while hiding in the sewers. El Diablo (Jay Hernandez) surrenders to the police after accidentally killing his wife and children.
They're all locked up in Belle Reve by Amanda Waller (Viola Davis), who wants to use them as disposable assets for the United States government, but her superiors reject her proposal.
June Moon (Cara Delevigne) touches a voodoo doll and becomes possessed by an evil spirit, the Enchantress. Waller tries to use her as a proof of concept of the potential of using meta-humans as living weapons, but the Enchantress goes rogue and releases her brother, the Incubus, who possesses a businessman (Robin Atkin Dawes). They besiege Midway City and turn people into monstrous creatures.
The government authorizes the Suicide Squad to go in and extract Waller. They're put under the command of Rick Flagg (Joel Kinnaman) and joined by Katana (Karen Fukuhara) and Slipknot (Adam Beach) and have nanobombs injected in their necks.
Meanwhile, the Joker finds out Harley is in Belle Reve and kidnaps one of the guards, Griggs (Ike Barimholtz), who directs the Joker to the facility where the nanobombs are created. The Joker then kidnaps one of the scientists and forces him to disable Harley's nanobomb.