The alien space station J7, the mid-1980s Earth time. The Time Lords have sent the second Doctor and Jamie here to try to stop dangerous experiments into time travel. But the station comes under attack from the Sontarans and far away in space and time the sixth Doctor goes into psychic shock...

The Doctor and Peri meet Jamie and learn the Second Doctor is with the Sontarans on Earth.

The Sontarans prepare the Second Doctor to trigger their Kartz-Reimer capsule.