DCI Jack Quant is stuck at a dead end. He can't convince his boss that the missing person he is investigating is something more. He can't sleep at night because of what happened to his mentor, it's all getting a bit much until suddenly Jack gets a friend request from the 'Interrailer killer' and that's when things really go into overdrive. Suddenly Jack is plunged into the middle of a case that reaches across the whole of Europe, with MI5 following his every move, a killer who likes to send personal messages and a possible mole in the department. Can it get any worse? For Jack it can...