SUICIDE SQUAD opens with an extended sequence detailing each character's incarcerations and transfer to Belle Reve Penitentiary. The sequence is set to pop music and each time a new character appears, his name and rapsheet appear on screen in bright neon colors.
Deadshot is an ex-military turned contract killer who once tried to kill the Batman, only for his daughter to place herself between him and Batman, defending Batman, and leading to Deadshot being arrested and harboring an intense hatred of Batman.
Killer Croc is a cannibal who lives in the sewers and works as a mucle-for-hire for other criminals. He was arrested by Batman.
El Diablo is a former gangster from a Los Angeles cholo gang who repented after he accidentally set his wife and children on fire, and is now a pacifist who refuses to use his powers.
Captain Boomerang is a mercenary who got busted by the Flash during a botched assassination.
Slipknot is also a mercenary and got caught by Batman.
Katana is not a criminal, but her late husband was a killer for hire, and she volunteers to work for the government to atone for his crimes.
Enchantress is an archaeologist working for the government, who is searching for evidence of ancient aliens when she touches a voodoo doll and gets possessed by a spirit witch.
Culminates with Harley Quinn, a psychologist who became infatuated with the Joker after he tortured her and ultimately became his girlfriend. The Joker actually likes Harley even though he treats her like ****. Batman busts a deal between the Joker and a weapons dealer, Monster T, and the Joker ditches Harley in order to escape. Batman brings both Harley and Monster T in.
The Joker is a gangster and owns a nightclub where Harley is an exotic dancer. Early on the movie, right before Batman busts them, the Joker has Monster T and his men in his private room, and notices one of Monster T's guys eyeing Harley. He goads the guy into accepting a lap dance, then kills him for disrespecting his girl.
Amanda Waller gets everyone under the same roof at Belle Reve and requests that the government let her use them as disposable assets in high-risk missions, but the government says "no".
Enchantress escapes and attacks Midway City, opening a portal to Hell, turning Monster T into her brother, the Incubus, and turning Waller's men sent after her into monsters. With no other option, the government lets Waller use the Squad, and Enchantress' ex-boyfriend Rick Flagg gets assigned to the team.
The Joker finds out that's where Harley ended up and shoots down the Squad's chopper above Midway City, but his crashes as well, and he's presumed dead.
Slipknot tries to ditch the team, and gets his head blown up because Waller has put bombs in everyone's necks.
They basically make their way through the city to reach the Enchantress' nest, fighting a bunch of monsters along the way.
The Enchantress kidnaps Waller to get her heart back and go max power. This gives the Squad the chance to escape, but they decide to see the mission through.
Harley destroys the heart, "curing" the Enchantress' host, and Diablo sacrifices himself to kill the Incubus and close the portal.
The mission is succesful enough that the government decides to keep using the Squad. Everyone is locked back up for further use, under Flagg's command.
Batman helps Deadshot see his daughter again and Deadshot becomes cool with him.
In the end, the Joker turns up disguised as a guard in Belle Reve and rescues Harley and they drive off into the sunset.
Boomerang, Croc and Katana are all pretty wasted.
That's a much better run time to flesh things out a bit, and not too long it will be boring, I hope 
but thanks for the warning now I don't feel so tempted 
