The once-feared Cybermen have disappeared from the universe without trace. An expedition from Earth arrives on Telos - homeworld of the Cybermen - to try and discover exactly what has become of the silver giants. Soon after the Doctor, Jamie and Victoria join the archaeological party, the first mysterious death occurs. With the group now stranded on Telos, it becomes clear that the Cybermen may not be as 'dead' as it was first thought. Beneath the planet's surface, giant ice-tombs hold the last remains of the Cybermen in a frozen sleep. And someone is working to re-activate them from their slumber...