The Mystery Chinese Puzzle (as it was referred to within the International Gallery) was a work of art by Giuseppe di Cattivo which appeared to be a Chinese puzzle box, which he created after having been driven insane by The Abomination. It was the key used to unlock and release the creature inside the painting.
When the Mona Lisa came to life, Lionel Harding destroyed the Puzzle Box in an attempt to stop her from freeing her "brother", The Abomination. However, Luke told her that he had an idea of how The Abomination could still be freed, and demanded she take them to Clyde Langer. Once she did so, Luke handed Clyde's sketchbook to him and told him to draw a new puzzle box based on a picture of it, which the Mona Lisa could then use her strange power to make 2-D paintings manifest into 3-D reality on. Clyde was hesitant to do so, knowing what she intended, but trusted Luke's judgment.
Once Clyde drew a new puzzle box on a page of his sketchbook, Luke tore off that page and handed it to the Mona Lisa, dropping the sketchbook on the ground nearby. The Mona Lisa brought Clyde's drawing to life and used the new Puzzle Box to awaken the Abomination. However, unbeknownst to her, Clyde had drawn K9 Mark IV on another page of the sketchbook earlier, and the Mona Lisa had inadvertently brought that drawing to life as well. K9 erased the Abomination, causing all the paintings that had been made real (including "K9") to return to their original forms and all the real people who had been trapped in paintings to be freed. (TV: Mona Lisa's Revenge [+]Loading...["Mona Lisa's Revenge (TV story)"])