Mysterious happenings at Camp Crooked Lake have the twins solving another mystery.

Mary-Kate and Ashley must find a missing robot before the science fair is cancelled.

Patty O'Leary invites all her friends, including Mary-Kate and Ashley, to a sleepover party in a toy store. When all the best toys start vanishing, the Trenchcoat Twins suspect there's an uninvited guest hiding in the store. Can they catch the thief or will Patty's party be a bust?

While having the time of their lives at summer camp, Mary-Kate and Ashley are accused of a crime they didn't commit. Someone's been stealing other campers' care packages and blaming it on them! Can the Trenchcoat Twins prove their innocence and find the real thief before they're sent home?

While visiting the U.S. Space Camp, Mary-Kate and Ashley search for clues that will explain why the space shuttle was covered with hundreds of mysterious holes.

Someone is trying to sabotage Ashley's chances to lead the cheerleading squad.

Mary-Kate could be kicked out of the upcoming horse show if the Trenchcoat Twins do not find out who at the horseback riding school keeps putting Mary-Kate's horse in the wrong stall and feeding it the wrong food. Original.