Nobody's Perfect — Donald E. Westlake

Dortmunder and company are off again in pursuit of the Big Score--hired by one Arnold Chauncev to heist a priceless oil painting from his fashionable Manhattan town house.

The scheme is foolproof: Chauncev collects from the insurance company, pays the gang handsomely for its professional efforts, and winds up with both a tidy profit and his cherished artwork back. And, as Dortmunder says, it was the best worked-out goddamn plan he'd ever seen in his life. Simple? Not quite.

Chauncev and Leo Zane, a hired killer, soon reappear to force Dortmunder and the others to travel to England and resteal the painting-- or is it a forgery? -- from the most well-guarded auction house in the world. As the action moves from New York to London to Scotland and back, the mishaps and misunderstandings weave themselves into the wildest and most hilarious fiasco by_ which Dortmunder has yet been overwhelmed.