Rough Weather by Robert B. Parker

A hurricane hinders a kidnapping and Spenser goes on a search for the man responsible - the infamous Gray Man, who has both helped and hunted Spenser in the past. Heidi Bradshaw is wealthy, beautiful, and well connected - and she needs Spenser's help. In a most unlikely request, Heidi, a notorious gold digger recently separated from her latest husband, recruits the Boston P.I. to accompany her to her private island, Tashtego. The reason? To attend her daughter's wedding as a sort of stand-in husband and protector. Spenser consents, but only after it is established that his beloved Susan Silverman will also be in attendance.