Johnny The Christmas Mouse is about a story of a city mouse who unexpectedly goes on an adventure due to falling into a lady's bag. He ends up at a nursery where he gets hit over the head by a sassy mouse named Lilly. He meets her youngsters and while recovering from flu tells them about the city and holiday traditions like Christmas. In turn, they teach him to do gardening. Johnny and the youngsters become very close, but when he unexpectedly gets an opportunity to go back to the city, he leaves on short notice without saying goodbye. Back in the city, he realizes he misses them.
Johnny decides to pack treats and presents and go back to ask for forgiveness and give them their first Christmas ever. They are overjoyed to see him and they are amazed at all the treats. Together they pick out a tree and on Christmas, he hands them their gifts, showing them how much he loves each one of them.
In the end, the little ones present him with a little ornament for the tree that looks just like him. Years later Johnny's tree decoration hangs on a human tree, reminding everyone what Christmas is really about. Love and family.