It's time for the annual Junior Bike Race in Bayport, and Frank and Joe are the top contenders. Midway through the race, Frank runs over a nail and blows a tire. It seems as if the day couldn't get worse--until Frank's bicycle goes missing! <P>Bayport's leading bully, Adam Ackerman, seems to be the prime suspect. But when he proves that he wasn't the bicycle thief, everyone turns out to be a potential culprit--even Mr. Mack's dog, Lucy! Can Frank and Joe crack the case and bring Frank's bicycle home?