To face a script in which most of the plot revolves around the dialogue of only two people in one location must be terrifying. Thank goodness for Katharine Hepburn and Humphrey Bogart. John Huston's adaptation of C.S. Forester's The African Queen was solid. And the decision to film on location in Africa helped develop the concept of nature as a viable character within the plot helps solidify the film. But without Katharine Hepburn, and Humphry Bogart, this film could have been reduced to a nice little travelog on the beauty and terror of African and the pretty animals living there. Within The African Queen each character undergoes metamorphosis. Charlie Alnutt grows from an apathetic man who enjoys the inside of a bottle, to a courageous man. Rosie in turn allows herself to be human, and vulnerable perhaps for the first time in her life. With lesser actors these changes would have appeared rushed, unexplained,and a dull beginning to an inexplicable romance. But it isn't. It's a captivating film. Rosie's brittle smile, Charlie's face as his vices are destroyed, these are moments of brilliance in an incredible film. I highly recommend it.
It's also worth noting that this was not an easy film to make. These performances survived crew and cast illnesses, constant mechanical errors and inclement weather. For more about the conditions it was created under, I suggest you read Katherine Hepburn's The Making of The African Queen or How I went to Africa with Bogart, Bacall and Huston and almost lost my mind. She's not the sanest author in the world, but all the more enjoyable.