NOTE: This spoiler was submitted by Jeremy

The film opens at Belle Reve Penitentiary where Brian Durland/Savant (Michael Rooker) is in his break room throwing a ball around at targets that he has precisely set up. He even uses his skills to bounce the ball off the walls and kill a canary. He is then pulled away by Amanda Waller (Viola Davis) as she assigns him to a task.

Savant is thrown into Task Force X/The “Suicide Squad” alongside Blackguard (Pete Davidson), Captain Boomerang (Jai Courtney), Weasel (Sean Gunn), Mongal (Mayling Ng), Javelin (Flula Borg), The Detachable Kid/TDK (Nathan Filion), and Harley Quinn (Margot Robbie). Led by Rick Flag (Joel Kinnaman), the team travels to the island of Corto Maltese for their mission. Upon arriving, Weasel falls into the water and apparently drowns since nobody knew he couldn’t swim. When the Squad makes it to land, Blackguard steps out and reveals he brought the team to the mercenaries waiting for them on the beach. For his troubles, he gets his face blown off. Harley goes in blasting while Boomerang throws his signature weapon to slice some heads off. TDK’s arms pop off so he can use them as (ineffective) weapons. The mercenaries retaliate and shoot TDK and Javelin dead. Mongal attempts to bring a chopper down but it crashes and she burns to death. Boomerang is impaled with wood and then shredded by the chopper’s blades. Harley and Flag go missing while Savant attempts to flee the chaos. Although Waller warns him, she detonates the explosive in the back of his head, causing it to blow up. She then sends in her second team to finish the job.

Three days earlier – Waller goes to recruit Robert DuBois/Bloodsport (Idris Elba), a deadly mercenary who is there for putting Superman in the ICU with a kryptonite bullet. Her leverage against him is Bloodsport’s teenage daughter Tyla (Storm Reid), who is in danger of serving time for stealing. The two argue loudly, as Tyla makes it clear that Bloodsport was a bad father. He goes to threaten Waller into releasing Tyla, but she knows he is going to comply regardless. After he relents, she introduces him to her other recruits – Christopher Smith/Peacemaker (John Cena), a patriotic mercenary; Cleo Cazo/Ratcatcher 2 (Daniela Melchior), who has the ability to control rats and keeps one named Sebastian close by; Nanaue/King Shark (Sylvester Stallone), an underwater prince with a taste for human meat; and Abner Krill/Polka Dot Man (David Dastmalchian), a man with an unusual genetic disorder whose specialty is throwing weaponized polka dots.

Waller informs the team about the situation in Corto Maltese – the nation was overthrown by a dictator named Silvio Luna (Juan Diego Botto) and his right-hand man General Mateo Suarez (Joaquin Cosio) after they executed the presidential family. They are operating in a Nazi-era research facility called Jotunheim where they are conducting dangerous experiments, codenamed “Project Starfish”. The Squad is assigned to find Dr. Gaius Grieves/The Thinker (Peter Capaldi) since he can lead them to Jotunheim and they can destroy whatever is going on in there. We jump to the facility where Luna and Suarez are observing their work, a gigantic starfish alien creature.

Presently, while Team 2 is making their way through the jungle, they come across a group that they believe to be mercenaries in league with the military, so the Squad kills them before they make it to the camp where Flag is hanging out with his contact Sol Soria (Alice Braga), a dissident whose team, the Freedom Fighters, is trying to take Corto Maltese back from Luna and Suarez…and unfortunately her team was the group that the Squad just killed. The team walks out of the jungle when they notice Polka Dot Man glowing different colors. He explains that his condition happened because his mother worked at STAR Labs and experimented on him and his siblings to give them superpowers. His condition forces him to drain the dots out of him or he will die, and he views all of his enemies as his mother before killing them. Before heading to Jotunheim, Flag insists that they recover Harley.

Harley has been taken captive by Luna’s men, but he brings her to his room to woo her since she is seen in the country as a symbol of anti-American anarchy. Harley is initially charmed by him, and he even asks her to marry him. However, when he reveals his plan of using whatever is in Jotunheim to eliminate anyone who threatens his regime, even if it means killing children. This crosses Harley and she shoots Luna dead, leading to his men to capture and imprison her.

The Squad is being taken by Sol’s contact Milton (Julio Cesar Ruiz) to go to a bar called La Gatita Amable where they will find Thinker. On the road there, Ratcatcher asks Bloodsport why he is afraid of rats, as he is always recoiling around Sebastian even though, according to Cleo, he sees good in Bloodsport. DuBois states that his father once punished him with rats, and it lead to his phobia. When he asks her why she is so drawn to rats, she explains that her father, Ratcatcher 1 (Taika Waititi), taught her how to control them but also treat them as family, but he was a drug addict and ultimately overdosed when she was a child. Bloodsport and Ratcatcher promise to one another that they will get each other out alive. The team makes it to the bar, but Nanaue has to stay behind since he will stick out.

The Squad drinks and dances before they spot Thinker. They apprehend him, but the military comes in to search everyone since they know that there are Americans in there. Bloodsport sends Ratcatcher outside with Thinker while he, Peacemaker, and Polka Dot Man are all taken in. On the road, the three subdue the gunmen and kill the driver before their van is run off the road. Ratcatcher and King Shark arrive with Thinker in tow.

Harley is being tortured by Suarez’s men for information, but she never budges. When she is left alone with his guard, she snaps his neck with her legs and sets herself free. Harley proceeds to shoot down Suarez’s guards before getting her hands on some blades and Javelin’s…javelin to slaughter her way through the guards. Outside, Flag tries to lead the Squad to rescue Harley until she shows up and joins them. They then get Thinker and order him to get them inside Jotunheim.

Once inside (and after Milton is killed), Thinker leads the Squad to the creature that he calls Starro The Conqueror. Peacemaker and Nanaue set up bombs all over the place. Thinker reveals to the Squad that the American government was behind the experiments involving Starro since they have been secretly funding Corto Maltese for decades. Starro also emits smaller starfish that attach themselves to human faces and take over their bodies like zombies, and there are slews of corpses of Starro’s other victims all over the facility. Starro breaks free and grabs Thinker, tearing him in two and splattering him across the wall. Flag attempts to secure the hard drive with evidence against the American government to deliver to the press, but Peacemaker turns on him per Waller’s orders. The two fight each other, with Flag nearly choking Peacemaker to death, but he stabs Flag through the heart with a piece of a broken sink. Ratcatcher witnesses this and grabs the flash drive while Peacemaker attempts to kill her. Meanwhile, Nanaue comes across small fish that mimic him, until their aquarium is broken and they begin to leech onto him, all while Bloodsport, Harley, and Polka Dot Man try to survive the crumbling facility. Bloodsport manages to survive going through several stories before he lands and witnesses Peacemaker getting ready to execute Ratcatcher. The two mercs draw their guns and fire their bullets at each other, with Bloodsport’s bullet breaking through Peacemaker’s and striking him in the throat, bringing him down.

King Shark falls outside and is shot by Suarez’s men, but he rises and bites the head off one gunmen before the rest of the Squad runs out of the facility as Starro bursts out. It releases more starfish that kill Suarez and his men and then proceeds to make its way into the city. Waller declares the mission over since the evidence is destroyed, but the surviving members want to save the city. Waller threatens to detonate their devices and kill them on the spot until her subordinate, Flo Crawley (Tinashe Kajese) brains her with a golf club and has the rest of the team guide the Squad to save the city. At the same time, Sol and her team execute the remaining members of the regime to stage their coup and take their country back.

Bloodsport begins blasting away at Starro while King Shark goes “nom nom” on the alien and starts to bite into it. Polka Dot Man envisions Starro as his mother and unleashes his polka dots to burn Starro’s leg, but the alien crushes him. Ratcatcher tries to use her beacon to summon the rats, but Bloodsport pushes her out of the way before she is killed. She then uses the beacon and gets practically every rat in the city to take down the infected citizens and start to take Starro down. Harley then charges into Starro’s eye with the javelin and breaks through before the rats make their way inside and take Starro down from the inside, finally killing it and saving the city. The Squad’s heroics are broadcast on the news, and Tyla acknowledges her father as a hero.

Bloodsport contacts Waller, ordering her to let the team and Tyla go free, or they will leak the evidence from the laboratory to the press. She reluctantly agrees and calls for the chopper to bring them home. As the team rests, Sebastian crawls onto Bloodsport’s leg, and he begins to pet the rat.

Mid-Credits Scene: Weasel is shown to still be alive and starts wandering into the jungle of Corto Maltese.

Post-Credits Scene: Waller’s subordinates John Economos (Steve Agee) and Emilia Harcourt (Jennifer Holland) are brought to a room where they find that Peacemaker is still alive, because Waller needs him, as Harcourt puts it, “to save the fucking world.”

Brought to you by

Amanda Waller recruits two separate teams of Task Force X to infiltrate the island of Corto Maltese and destroy a laboratory called Jotunheim, where the current corrupt regime led by President Silvio Luna and General Mateo Suarez are conducting experiments to use against dissidents, codenamed "Project Starfish". The first team, led by Rick Flag (Blackguard, Mongal, The Detachable Kid, Weasel, Captain Boomerang, and Harley Quinn), all die horribly, with the exception of Harley, who is captured while Flag is taken by a contact of his and her team of dissidents.

The second team (Bloodsport, Ratcatcher 2, Peacemaker, King Shark, and Polka Dot Man) make it to the island and find Flag. They go get Harley, who has killed Luna and escaped captivity by killing Suarez's men. The team tracks down a metahuman mad scientist named The Thinker to get them into Jotunheim, where he reveals the basis of their experiment, a gigantic alien called Starro The Conqueror, who emits smaller starfish to mind-control people and wear their bodies out. What's more is that the American government was in on this since they secretly funded the experiments in Corto Maltese. Starro breaks free and kills Thinker while Flag attempts to secure evidence, but Peacemaker kills him per Waller's orders to keep a lid on America's involvement in this. Bloodsport shoots Peacemaker when he tries to kill Ratcatcher, and Starro uses the starfish to kill Suarez and his men before going on a rampage across the city. The remaining members of the Squad choose to save the city, and when Waller threatens to kill them for going off-mission, her subordinates bring her down to help the Squad. They utilize their special skills to fight Starro and kill it before being allowed to go home and go free now that they have leverage against Waller.

The credits reveal that not only has Weasel survived on the beach, but Peacemaker is also still alive and is being kept by Waller for future missions.