Monte Carlo, 1966.
Four time travellers. Two missions. One costumed ball. the Doctor has sent Peri and Erimem to prevent the fabulous Veiled Leopard diamond from being stolen. Which is odd, seeing as the Doctor has sent Ace and Hex to steal the diamond. How will the two teams cope with this contradictory task? Will Peri's asp slip? Why does Ace have to pretend to be a French maid? How will Erimem cope with Pharaoh Rammalamadingdong? And can Hex really 'do posh'?