Celine, Felix Fox and Benny Bear discover a locked treasure box in the school library and solve three clues to uncover its combination. When the correct numbers fail to open the box, they examine the lock more carefully, discover that the numbers must be rearranged, and then solve a second problem involving a hidden latch. A clever puzzle story that teaches logical thinking, careful observation, sequencing, checking assumptions, and understanding that correct information must also be used in the correct way.