The narrator visits Simon Wheeler in a tavern in Angel’s Camp, Calaveras County, California, a gold rush mining town. He calls on Wheeler at the request of his friend from back East to ask after the Rev. Leonidas W. Smiley. He finds Simon Wheeler dozing by the stove and describes him as old, fat, simple, and gentle. As Wheeler backs the narrator into a corner and launches into a series of tall tales about a completely different man named Jim Smiley, the narrator suspects that his friend made up Leonidas as a pretext to entrap him into listening to Wheeler’s “long and tedious” stories.
Wheeler’s story within the story commences, all about a gambler named Jim Smiley. Jim Smiley would bet on anything. He was a lucky man who almost always won. He bet on dog fights, horse races, and even the ill health of the parson’s wife. Smiley trained animals to win bets for him. Both his horse, the "fifteen-minute nag," and his dog, “Andrew Jackson,” didn’t seem like much, but would surprisingly win in the end. Andrew Jackson had a trick during a fight of catching the other dog’s back legs in his mouth tenaciously. This worked until he fought a dog that didn’t have back legs. When Andrew Jackson didn’t know what to do, he looked heartbrokenly at Smiley and died. Wheeler comments that the dog probably had some “genius” and “talent” in him, since he managed to come out on top despite lack of opportunities.
Smiley caught a frog, named him Dan’l Webster, and took him home to “educate” him. For the next three months, he did nothing but teach the frog. It could turn somersaults in the air and catch flies on command. Dan’l Webster’s specialty was to jump higher than any other frog around. Despite his many gifts, he was "modest and straight-forward.” Jim Smiley kept Dan’l Webster in a box and would occasionally fetch him for a bet.
One day, a stranger in the camp asks Smiley what’s in the box. Smiley responds indifferently that it could be other animals, but it’s a frog. The stranger examines the box and asks what the frog is good for. Smiley replies casually that he can outjump any frog in Calaveras County. The stranger replies that he doesn’t see anything unique about that frog. Smiley says, "May be you understand frogs, and may be you don't understand 'em; may be you've had experience, and may be you an't only a amature, as it were. Anyways, I've got my opinion, and I'll risk forty dollars that he can outjump any frog in Calaveras county."
The stranger thinks about it, and then says that if he had a frog, he would take the bet. Smiley offers to catch him a frog, and hands the box with Dan’l Webster to the stranger. While Smiley is out, the stranger takes Dan’l out of his box, opens his mouth, and fills him with quail shot. Then he sets him on the floor. Smiley comes back from the swamp with a frog and gives him to the stranger. They set the frogs side-by-side with even fore-paws. Smiley calls “One two three jump!" and they each touch their frogs from behind. The new frog hops off. Dan’l Webster tries to jump but can’t budge. Smiley is surprised, disgusted, and confused. The stranger takes the money and starts away, and as he’s leaving repeats what he said earlier about not seeing anything special about Dan’l Webster. Smiley scratches his head, stares at his frog, and wonders aloud what happened. He’s concerned that there’s something the matter with Dan’l Webster, as he looks “mighty baggy, somehow." He picks up the frog and exclaims that he weighs five pounds! When he turns Dan’l Webster upside down, Dan’l belches out a double handful of shot. Smiley realizes that he has been swindled, and runs after the stranger angrily, but fails to catch him.
Simon Wheeler’s story gets cut off when he hears his name called from the front yard and goes out. He tells the narrator to wait, he won’t be long. The narrator figures he won’t find out anything about Leonidas W. Smiley, so he starts to leave, but encounters Wheeler again in the doorway. Wheeler begins to tell the narrator another tall tale about Smiley’s yellow one-eyed cow without a tail. The narrator interrupts good-naturedly, says goodbye, and leaves.
