Ironwood by Michael Connelly

Stilwell is the top law enforcement person on Catalina Island. He and his team get word that a drug drop is happening, but the team is ambushed and Stilwell then has to find out who was responsible. In addition, Stilwell gets to assist Renee Ballard of the LAPD's Open-Unsolved Unit when cases that both are working on turn out to be connected. A solid second book in the series that's hard to put down.