Unknown forces bring to life Leonardo Da Vinci's most famous painting, and Clyde's day becomes a nightmare when a school trip descends into disaster. Trapped and without Sarah Jane's help the gang must find a way to battle the awesome abomination.

As Luke and Rani investigate the myth of the dreaded abomination, Mona Lisa vows to free her horrifying brother from his prison, but everything now depends upon Clyde to stop the terror.