The three THREE QUESTION MARKS kids 91 - Danger in the hall of mirrors

Uncle Titus acquires an old mirror maze. The labyrinth of mirrors and glass walls provides the three ??? kids with plenty of fun. But then they come across strange floor tiles that light up in colors when touched and trigger an eerie riddle song. Why? The three friends hope to find answers from the famous riddle inventor Mr. Think. However, when they arrive at his villa, there is no sign of him. Has Mr. Think been kidnapped?.