Paperback edition, 224 pages.
 
The key to Earth's destruction lies buried in its past.Visiting Paris in 1979, the Doctor and Romana’s hopes for a holiday are soon shattered by armed thugs, a suave and dangerous Count, a plot to steal the Mona Lisa and a world-threatening experiment with time.
 
Teaming up with a British detective, the Time Lords discover that a ruthless alien plot hatched in Earth’s pre-history has reached its final stage. If Scaroth, last of the Jagaroth, cannot be stopped then the human race is history, along with all life on Earth…