A more fully rounded performance than his earlier films, this pairs Martin with Lily Tomlin — in the same body. A diffident, jazz guitar-playing attorney, he accidentally becomes the repository of the soul of rich, unpleasant Edwina Cutwater (Tomlin), who takes up residence in the right side of his body. As he still controls the left side, simple tasks like walking become major feats of coordination, and more complex procedures like urination take on a decidedly dangerous aspect.
This was the film which revealed that Martin's comic talents went much further than big-yuk mugging, and that he could actually act better than most so-called "straight" thespians.