Christmas is fast approaching, so Barney and the children are quite excited. They help decorate the caboose for the holidays and build a "thinking" snowman in the park. Then they visit a tree planted by Beth's great-great-grandfather that's now the prettiest, oldest one in the park. Her grandmother is in charge of decorating the tree for Christmas this year, and everyone is shocked to find that the large star to adorn the top is missing! Grammy suggests it's up in her attic and dispatches Barney and the children there to find it. Fun and playful mayhem ensue, with constant distractions from the search by various and sundry dusty "treasures" encountered. The kids, Baby Bop, and B.J. discover--and become--old-fashioned toys. All dictate a musical letter to Santa, typed on an old fashioned ty