THE COCKROACHES, by Jo Nesbo.
As Hole pursues the killer, the body count mounts; including his own if he's not careful. Being handcuffed to the drain at the bottom of his hotel's swimming pool brings home to Hole just how dangerous Bangkok can be. It's a 5; plenty of violence, no corners cut, tension and action, plus plenty of internal dialogue as well. Makes Stieg Larsen look very very tame. Stellar!