The First Rule, Robert Crais, 2010 

A fine Joe Pike novel in which the former Marine and mercenary avenges the death of a former mercenary who served under him in Kuwait and elsewhere and who along with his family is murdered in a home invasion.  The Serbian mob in LA turns out to be the bad guys, and Pike teams up with John Sloan (former mercenary), Elvis Cole, and a fed from ATF who all combine to kill the bad guys and save a 10 month old baby at the same time.  Hard-to-explain light fare for the summer.