Last boy standing

Special Agent Bex arranges to meet teenage Kieron in a caf to tell him that she can't risk his life any more. She parks her car and seconds later it blows up, scattering flaming wreckage everywhere. She needs to get Kieron out of danger's way--but just as they get to the flat, it too explodes. Bex is forced to face the possibility that someone wants to kill her team, but whoever it is doesn't know about Kieron. That may be their only saving grace. But how were the explosions managed? And who wants them dead?