67 books • 23 series
Agent Arthur's Desert Challenge (Usborne Puzzle Adventures S., #19) (Puzzle Adventures) (Usborne Young Puzzle Adventures S.) (Puzzle Adventure S.)
Agent Arthur's Arctic Adventure (Puzzle Adventures, #12) (Puzzle Adventures, #12) (Puzzle Adventures, #12) (Usborne Puzzle Adventures) (Puzzle Adventure S.)
Search for the Sunken City (Puzzle Adventures, #14) (Puzzle Adventure S., #14) (Puzzle Adventure)
The Intergalactic Bus Trip (Usborne Puzzle Adventures S., #5) (Usborne Puzzle Adventures)