The body of a young woman is found in a Stockholm hotel room. It appears that she has been strangled after a night partying with two young men, but the room was paid for using the credit card of a mugging victim whose alibi doesn't add up. Martin and Gunvald investigate under the supervision of their new boss Klas Freden.

The bodies of two buried men are found and despite persistent attempts, they cannot be identified. When another man is murdered they discover new evidence that soon leads them to an Islamist terrorist cell.