Carol contracts laryngitis and may not be able to sing at the holiday service, so Cindy asks a department store Santa Claus for a miracle.
The Bradys are excited about spending their first Christmas together as a combined family. Carol has been chosen to sing the solo at the Christmas morning church service, so Mike decides to buy her a tape recorder for Christmas so that she can keep a recording of herself singing. But Carol's practicing and the tape recorder may all be for naught as days before Christmas, Carol loses her voice. Luckily, she finds out that she is afflicted with nothing more serious than vocal strain induced laryngitis, but that still does not provide any comfort in that if it does clear by Christmas, she won't be able to sing at the service.
Regardless, all the Christmas chores still have to be done, and Alice does her part by mixing up a Nelson home remedy, however intolerable, to help Carol get past her laryngitis. But Carol's laryngitis places a pall over the entire family, so much so that the older kids contemplate cancelling Christmas altogether.
Cindy takes this feeling to an extreme when, on Christmas Eve, as her mother feels no closer to regaining her voice, she asks the department store Santa Claus for her mother's voice back so that she can sing at the church service, to which the Santa, unable to deny Cindy anything she wants, promises that he will do so. This promise brings up a problem for Mike, who has to try and explain to Cindy why her mother probably will not get her voice back by Christmas, while not bursting Cindy's innocent notions of the magic and spirit of Christmas.