Three children and their frolicsome pooch Capers are aroused when their favorite mailman old Joe Patches is pushed off the road by a ""walking tree"". An investigation of Dark Entry, an old haunted house, turns up a letter for Mrs. Patches announcing her inheritance-a great fortune left by an eccentric relative. Further probing by the three reveals a treasure chest buried in an old mine shaft. Harassment occurs along the way in the form of an attempt to poison Capers, a robbery of some vital books from the town library and several more dangerous obstacles deliberately thrown in their path. The villain turns out to be Mr. Revere, the man who posed as postal inspector, but who is in reality an old vaudeville actor capable of assuming many disguises even including that of a tree. The children are amusing and authentic and their adventures hold interest. The most flagrant flaw is in the plot which requires all loose ends hastily tied up via several pages of final explanation.