I Will Fear No Evil

I Will Fear No Evil is a science fiction novel by Robert A. Heinlein published in 1970. The plot concerns a wealthy businessman whose brain is transplanted from his dying elderly body into the young, healthy body of his female secretary, coincidentally killed in a traffic accident -- and whose personality continues to co-inhabit the body.

Depending on how you choose to view it, the novel may be read as either a riveting exploration of human relationships and the need to treat our fellow man decently while we're still alive, or as the rambling sexual fantasies of an old man with a brain tumor.