The Old-Fashioned Mystery — Carolyn Keene

It's time for the Holiday Streetwalk in River Heights. That's when the stores serve cider and cookies, carolers sing on street corners, and there's face painting, clowns, and costumes for everyone to enjoy. But the best part is when the mayor turns on the Christmas tree lights and Mr. and Mrs. Claus arrive in a horse-drawn sleigh.

One lucky child will get to present Mr. and Mrs. Claus with the key to River Heights, and this year it's Bess Marvin! There will be reporters and TV cameras on the big day, but Bess's chance to be a star is ruined when the key to the city disappears. Can Nancy, Bess, and George unlock the secret of the missing key before Bess's special day is spoiled?