P. T. Barnum, best known for his own use of hoaxes in his popular Barnum & Bailey Circus, found that the use of hoaxes was acceptable when the audience was getting the entertainment they paid for. When it came to religious hoaxes, fraud, and swindling, Barnum was avidly against it. He even went so far as to offer $500 to any medium who could prove that they actually could reach the dead.

In this exposé of humbugs and the scams they perpetuate, he goes after religious quacks, witches and sorcerers, and other forms of frauds in all walks of life. He discusses some of the most notable scams of the time and reveals the perpetrators as humbugs. In addition to scams, he also discusses business affairs and his own opinions of the current events of his time.