High-flying financiers are being murdered and it is beginning to appear like the work of a serial killer. CID inspector Jenny Hultin puts together a team of top detectives to crack the case swiftly before there are more deaths and a national panic. One of the team, Paul Hjelm, is saved from a disciplinary hearing for shooting a hostage taker when he said he was unarmed. Together with his new colleagues he finds himself working 24 hours a day in shifts to find the killer quickly. They are A Unit and their pursuit of the Fat Cat Killer will expose tensions within the newly-formed group and put some of them in fear of their lives. And what do the financier killings have to do with the Estonian mafia and the discovery of a dead robber in an empty bank with a dart in his eye?