In case you don’t know why the Danes and the Swedes are working together, it's because a body was found severed on a border bridge. One half is in Denmark, the other is in Sweden. Hence the name. And now that you're hooked, this is what happens in this week's doubler: The murderer holds a bus full of schoolchildren hostage, and vows he will only let his captives go if members of the public set fire to the premises of five companies that indirectly benefit from child labour. Meanwhile, a witness statement leads Saga and Martin to arrest one of their colleagues on suspicion of masterminding the crime spree, but he appears to have an alibi for all the incidents.