Suspecting Lisa, his wife, of adultery, Peter tries to figure out why his wife had disappeared. When Lisa found out that she has cancer, she decides to leave him clues so that he could discover the affair and the secret life she had been leading and that he never knew existed. Peter sets out to track down the other man in her life.

Adapted from the memoirs of literary critic John Bayley, the film recounts his courtship of and long marriage to British novelist Iris Murdoch. The scenario tacks back and forth from the young Iris--ready to seduce one and all with her coy command of words and sex appeal--to the elder Iris--slowly giving way to the cruel erasure of Alzheimer's.