The orbit of the holiday planet, Azure, the year 2116. The starships Empress and Hecate are fused together after an accident in hyperspace. Naturally the Doctor thinks he can find a solution, but has the accident unleashed a far more deadly menace?

Two ships have collided above Azure but that may be the least of the Doctor's problems. Monsters and drug smugglers are loose on the ship. And it all seems to tie in with Tryst's electronic zoo…

The Doctor and Romana begin to uncover the truth about the strange events aboard the luxury liner Empress. They first have to separate the two ships from each other, but they've got Mandrells, drug smugglers and police chasing after them.

The Doctor finally discovers the truth about the drug smuggling ring. But the villains are still one step ahead.