Noting that the viewer is lost in the forest, he decides to recount the tale of Tiny, a Jack Russell Terrier puppy, the seventh brother (occasionally interspersing his story with various comments of his own).
The doctor's tale begins the previous spring, with Tiny the puppy riding in a car with his owner --- a little girl named Angie --- and her grandpa after an enjoyable trip to a big city.
Spotting a frog outside, Tiny goes after it, but falls down a hill (unbeknownst to his owners, who drive off without him and can't hear his barks over the storm).
Their opinions on him are mixed (most of them believe Tiny to be some form of monster), but the leader of the group --- the ruffian of the family, J.C. (his real name is Jerald Cuthbert) --- feels that he should be left to survive on his own; luckily, one of his sisters, Joanna, decides that they should help him.
She quickly convinces her siblings to join up after putting the matter to a vote with the other rabbits --- Rebecca (the eldest sister), Mimi (the sensitive one), Cody (the glutton), Marty (the cautious one) --- and Tiny is welcomed into the family as a "bunny-puppy".
J.C. and his father stay in their hole trying to dig their way out while the other rabbits climb up a branch, but Cody is caught in the raging waters and Tiny jumps in.
The puppy saves Cody, and the rabbits hop onto dry land, but J.C. and their dad are still in their hole trying to dig through as the water rises.
But he is sick due to the effects of the bite (as well as being unable to survive on vegetation like all the other forest animals), and he is taken to see Dr. Owl, who tells the parents that he must be returned to his owners.
One scene where JC is shown fighting a silhouette of Mickey Mouse was removed from the English version for copyright reasons.