The Fourth Hand by John Irving

While reporting a story from India, a New York television journalist has his left hand eaten by a lion; millions of TV viewers witness the accident. In Boston, a renowned hand surgeon awaits the opportunity to perform the nation’s first hand transplant; meanwhile, in the distracting aftermath of an acrimonious divorce, the surgeon is seduced by his housekeeper. A married woman in Wisconsin wants to give the one-handed reporter her husband’s left hand – that is, after her husband dies. But the husband is alive, relatively young, and healthy.