Terror of the Zygons

STORYLINE

When the Doctor, Sarah and Harry arrive in Scotland, having received an urgent request for assistance from the Brigadier, they discover that the mysterious force which has destroyed three oil rigs has left giant teeth marks on the wreckage.

The mystery deepens leading them to the shores of Loch Ness where they find that the legendary monster really does exist - and it's the murderous tool of the Zygons, aliens intent on overpowering the planet.

The Doctor and his companions must find a way to defeat the deadly Loch Ness Monster and its controllers, but the Zygons have the terrifying power to change shape and the Doctor is in grave danger when he finds that his friends and allies are not always what they seem...