One for Sorrow, Helen Fields

CI Ava Turner and DI Luc Callanach are under pressure: not only do they have to stop the bombings, but they realise that these are more than random attacks — every device may be a trap. 
As the body count rises and the bomber’s methods become increasingly horrifying, Ava and Luc must race to uncover the bomber’s identity — or face paying the ultimate price. 
There are twists and turns, and a secret that must be revealed before more lives are lost