Jimmy Stewart plays Elwood P. Dowd, a simple man who frequents bars and makes friends with derelicts (sounds like my buddy Lou). But even more unusual is his invisible friend, a 6' 3 1/2" white rabbit named Harvey.
Those most affected by Dowd's tall furry friend are his sister and niece that he shares a house with. Josephine Hull (also from Arsenic and Old Lace - another Must-Rent Movie) plays his frantic sister who's trying to put him in a mental institution. But when she drops him off, the medical staff thinks that she's crazy and comedy ensues.
This movie was adapted from a play, and is therefore very conversational - there aren't real action scenes - but it's fast-paced due to it's quick wit and comedic timing. Especially good are the moments when Dowd and Harvey are together, as the camera has allowed enough room for both to be in the frame.
One of the best lines from the movie that I strive to live by is spoken by Jimmy Stewart:
Years ago my mother used to say to me, she'd say, "In this world, Elwood, you must be" - she always called me Elwood - "In this world, you must be oh so smart or oh so pleasant." Well, for years I was smart. I recommend pleasant. And you may quote me.We will, Jimmy. We will.