While on holiday in Paris, the Doctor and Romana experience a time distortion. At the Louvre, someone is taking an unusual amount of interest in the Mona Lisa.
Scaroth intends to travel back in time to save his own people from destruction.
Templar receives a request for protection from a beautiful girl (June Ritchie) claiming to be Hitler's daughter; guest Noel Purcell.
Count Scarlioni is revealed to really be Scaroth, last of the Jagaroth and is funding the construction of a time machine – but for what purpose?
The Doctor and Romana become the reluctant guests of Scarlioni who is planning to steal the Mona Lisa despite having six Mona Lisas hidden in his cellar – all of them genuine.
