Robert Crais gives Elvis Cole and Joe Pike a day off, and spins a terrifically entertaining crime mystery starring Maggie, a US Marine bomb-sniffing dog who, after a near fatal ambush in Afghanistan that killed her Marine handler, is send to the LAPD K9 unit for another chance. K-9 is also a second chance for Scott James of the LAPD, a survivor of a shootout on LA's mean streets. James' partner and close friend, Stephanie, wasn't as lucky, gunned down in the mysterious assault leaving her and two others dead and five assailants unidentified. Scott was on the shortlist for SWAT, but with a shot-up leg and PTSD, he instead requests assignment to the K9 corps, where he's teamed up with Maggie. As his memory of the tragic event comes back in vague recollection, James works with the detectives to crack a case gone cold. The two stories: building the man and dog bond, intermeshed with James' obsession with avenging Stephanie's death and hopefully absolving his guilt, roll together for a fitting climax.