The story doesn't feature a "mesmerizer" in the traditional sense. It focuses on Jim Smiley, a gambler who loves to bet on anything, and his prized pet frog, Dan'l Webster. Smiley brags about Dan'l's incredible jumping abilities and challenges a stranger to a jumping contest. The stranger, however, uses a trick to win the bet, leaving Smiley devastated.
While there's no mesmerizer, the story does touch on the power of storytelling and the art of deception, themes that are woven throughout Twain's work.