Stu's stag do in South America goes bad when Greg collapses at customs and is found to be full of cocaine. Arrested, the group are taken to an island prison run by cocaine-smuggling siblings, Selma and Branco. Things go from very bad to much worse.

Stu et al watch Clem operate on Ant, while Selma learns about a case being built against her. Greg escapes to meet Stu - they were in on this together. Stu accidentally kills Greg as Selma finds the others, demanding to know Greg's whereabouts.

Under The Man's instruction, Stu gets the gang jobs in the prison coke factory while Hugo works a special job for Selma - the assassination of her brother at a dinner being thrown for their boss. Things go awry. Stu's betrayal unspools. Blood spills.

The gang under house arrest, Kai tricks Stu into admitting he put coke in everyone's cases and has a phone. The Man helps Branco see that Selma's behind Davide's murder. This means war. The minefield goes down, starting a mass escape attempt. Until...

Gemma and Selma are revealed to have surprising history. Cisco fights for his life. Stu, Ryan and The Man set their plan into motion before watching it fall apart. The Man has his heart broken and Clem, Gemma and Selma go tooth... nail... and claw.

Branco kills Selma. Clem wins a race to the surface and The Monster kills the loser: Gemma. The Man is mortally wounded and Kai gets his revenge on Stu. Stu and Ryan almost make it out together until they don't and Stu's left all alone. Or is he?