Every now and again, the BBC managed to draft in some heavyweights onto it's flagship "Dr. Who" series and this one is amongst the best. We get a clue of what's to come from the explosive start before the "Doctor" (Tom Baker) and "Romana" (Lalla Ward), who looks like she's just escaped from "St. Trinian's", arrive for a sojourn in Paris. Sitting in a café they experience some sort of time loop, then on a trip to see La Giaconda at the Louvre - one of the best museums in the galaxy, don't you know - they both begin to become suspicious that not only is the painting's safety in question, but the world's too. It's the enigmatic "Count Scarlioni" (Julian Glover) who is piquing their interest, him and his stylish "Countess" consort (Catherine Schell) and as their investigations dig deeper, they uncover an almost Dorian Grey-esque aspect to the story - only much more menacing in intent. This story has a go at a little more science than many, the visual effects are more effective as they are largely confined to a lab (OK, yes there's some latex too) and the effort from Glover works well to foil the time-travelling double act as they strive to thwart his nefarious activities. There's also a little bit of history, some pretty views of the Parisian sights and, of course, a mad scientist in David Graham's "Kerensky". Good stuff, this.