The frame story concerns a military governor's efforts to understand the basis of a local law that forbids the shaving of beards from fish on Sunday. None of his staff know anything about native fish growing beards, so he calls in the village mayor to explain the local law. The Mayor explains that his people believe one should not do unnecessary work on the day of worship and that the matter of the fish goes back three generations.
The Mayor recounts a story about a constable named Toby Case who has to contend with a young man named Jasper Shanks who claims that the Lord has shown him a miracle, a fish that grows hair. According to Shanks the miracle can be celebrated every Sunday if the fish is shaved. Shanks also wants donations to build a place to reenact the miracle. Reverend Talbot and Constable Case figure the money will go into Shanks's efforts to convince a father to approve his daughter's marriage to Shanks. Talbot and Case debate the dangers in this sort of movement, dismissing various measures to curtail it.
Toby scratched his unshaven chin. Being the Sabbath, it was, of course, illegal to shave in the shire. He grinned slowly. “Reverend, I think maybe this might be a matter for the Mayor and the Council.”
At the conclusion of his tale, Popins explains that the law is of great importance to him and his family. The frame story is a bit lengthy for my taste relative to the interior narrative, but the charm of Constable Case's clever solution to Shanks's "religious movement" makes up for any structural flaws.