Showing The First Rule by Robert Crais

Joe Pike is out for revenge and no cop, no bad guy, no one alive, is going to stop him.

Frank Meyer had got out of 'the life' safely. He had put an end to his mercenary days, turned over a new leaf and settled down with his wife and children. It had been a hard decision but, encouraged by his boss and friend Joe Pike, he had walked away.

Ten years later, a group of armed men break into his Los Angeles home and brutally gun down him and his family. It's a vicious, cold and professional job. The crew leave no trace behind except the bodies.

But they have made one catastrophic, and almost certainly terminal, mistake - Joe Pike. Because Pike is now determined to hunt down and eliminate everyone involved in the attack, one by one. And it doesn't matter that, as he starts to investigate, he discovers that these criminals are bigger and better organised than he ever could have imagined, because they are about to learn the first rule:

Don't make Joe Pike mad...