Bill James 
I am Gold [EPUB ebook] 

The twenty-seventh title in the popular Harpur and Iles series. A street shooting leaves a mother and child dead on the school run. But was this a random attack? Unlikely, when it transpires that the victims were the wife and son of well-known drug baron Mansel Shale. Having committed this atrocity, the gunman flees to a nearby shop where a hostage situation quickly develops. Detective Chief Inspector Harpur and Assistant Chief Constable Iles are brought in to oversee the siege – which ends in sudden tragedy. But as subsequent events unfold, it appears that the gunman wasn’t tracking Shale after all, but his wife . . .