 Martin is having some troubles with his spaceship, so he calls in some help from an old friend, one of the greatest minds ever on Earth: Leonardo Da Vinci. Da Vinci has other things on his mind than helping Martin. He is dismayed at life in the 20th century: how his inventions have been credited to others, and how his painting, La Gioconda, has been renamed the Mona Lisa. In his mind, all those have been stolen from him. The Mona Lisa is currently on loan to a local museum, for which Det. Brennan is in charge of security. Da Vinci sneaks out of the O Hara apartment to collect some of what he considers to be his personal belongings, including the painting, all in an effort to take home with him to the 15th century. Martin is afraid that he ll be able to figure out how to use the CCTBS to do so. Martin and Tim find Da Vinci back at the apartment ready to take off back to the 15th century with among other things the Mona Lisa, and in an effort to stop him, Tim destroys the painting. To preserve history, they ask Da Vinci to paint a new version of the painting. Needing a model, they use an unsuspecting Mrs. Brown. Da Vinci completes the painting, in his mind greater than the first, but a Mrs. Brown likeness of the Mona Lisa and not what the world knows as the Mona Lisa. Da Vinci refuses to compromise his artistic integrity, so Martin is forced to recreate the Mona Lisa himself. It may no longer be a true Da Vinci, but it ll fool the world. Da Vinci is satisfied, and takes off back to the 15th century solely with his new masterpiece, the Mona Loralei. Or so Martin and Tim think.