A dubious stranger - the main character of this book - gains access to a Mississippi steamboat and plays tricks on the other passengers. Everyone who gets involved finds himself in difficult conversations with the stranger, who specifically tests self-confidence, attitudes and moral standpoints. In the process, very different characters - including a numb person, a doctor, a manager - are brought into focus, and an overall situation unfolds that is not easy to interpret. In the end, the main character does not seem to be the only doubtful person...
This work by Herman Melville was long considered a failure, but today it is considered a satirical masterpiece.