Dragon's Claw

Sailing in the Tasman Sea Modesty Blaise discovers Luke Fletcher, one of Britain's greatest artists, lost in the middle of the ocean, alone on a raft, and with a strange gap in his memory. It leads her to the mystery of the nest of evil known as Dragon's Claw. Modesty and her loyal lieutenant, Willie Garvin, become involved in a complex of murder mysteries, struggling against the baffling activities of unknown enemies. Only when Modesty and Willie are helpless captives do they discover the identities of those they must overcome. Against them are a group of deadly killers working for an unknown master. The Reverend Uriah Crisp is an ordained minister and the greatest shot with a handgun in the world, and believes that his victims are sinners who deserve their fate. Beauregard Browne is a master of disguise and mimicry, who kills his victims using the famous handkerchief trick, and is accompanied by his county companion, Clarissa de Courtney - Scott. As usual ingenuity and resourcefulness help Modesty and Willie win the day as they escape Dragon's Claw and find themselves in a fight to the death.
https://en.wikipedia.org/wiki/Dragon%27s_Claw