Survival

The Doctor takes Ace back home to Perivale so she can catch up with her old friends. But Perivale has changed, the old gang has split up, and some of them have vanished without trace. They are not the only ones - West London is plagued by unexplained disappearances.

Before long the mysterious kidnappers make themselves known. A race of galactic hunters called the Cheetah people have found a way to transport themselves to Earth - and the entire human race is their prey. They have been shown the doorway to the planet by an old foe of the Doctor, a bitter and desperate enemy who needs the Doctor's help to free him from a diabolic enchantment.

As the Doctor tries to unravel the mystery, Ace finds some of her old friends, trapped on the savage and beautiful world of the Cheetah People. But the only way she can lead them to safety is to allow herself to succumb, like so many before her, to the curse of the planet. The Doctor realises that Ace's new powers will provide the only route home, but it will mean the sacrifice of her humanity to the most bestial and dark side of human nature...