River Heights is getting a carousel! And the town is having a special ceremony to unveil it. Nancy, Bess, and George are dizzy with excitement for their first ride on the beautiful antique horses. All the kids who ride the carousel can also try to grab a brass ring that hangs on a pole next to the carousel. Whoever captures the ring wins a special prize!

But suddenly the brass ring is gone, and without it the contest will be ruined. Nancy is on the case, but her head is swirling with too many clues. Can she solve this carousel mystery before it spins out of control?