Moshi Monsters: Katsuma and the Art Thief - Read it Yourself with Ladybird: Level 4 (Read it Yourself) (Paperback) - Common

Paintings have been stolen from the Googenheim Gallery and fake ones put in their place are making the Moshlings act very strangely indeed. Can Katsuma solve the mystery of the art thief and save the Moshlings from a nasty fate?