Dragon's Claw by Peter O'Donnell

While sailing a small yacht single-handedly from Australia to New Zealand, Modesty Blaise rescues Luke Fletcher, the world-renowned painter, from drowning. But how in the world did Luke Fletcher end up adrift in the Tasman Sea, after having disappeared in the Mediterranean two months earlier?Luke Fletcher is not the only person from the world of the arts who has disappeared recently, but he is the only one who has turned up alive. But then Luke Fletcher is killed, and Modesty and her loyal lieutenant Willie Garvin vow to find the killer.

The trail leads back to the Tasman Sea, to Dragon's Claw Island, but Modesty and Willie make a mistake and find themselves in captivity. They've solved the puzzle of the murders, but will they live long enough to bring the killers to justice