A wealthy woman has just recruited Spenser to accompany her to her private island to attend her daughter's wedding as a sort of stand-in husband. It should be a straightforward job for Spenser: show up for appearances, have some drinks but when Spenser's old nemesis Rugar - the Gray Man - arrives, Spenser realizes that something is amiss. A storm, a kidnapping, and murder tear apart what should be a joyous occasion, and Rugar is seemingly at the centre of it all. With six dead bodies and questions to answer, Spenser begins a search for answers - and the Gray Man.