The TARDIS arrives on an apparently deserted space station in Earth orbit, some time in the far future. Investigating, the Doctor, Sarah and Harry discover that the remnants of the human race are in suspended animation awaiting Earth's return to habitability following solar flares. The Doctor realises that the Earth is in fact now habitable again and activates the controls to begin reviving the humans. However, there appears to be something amiss - some controls are damaged (which is why the alarm clock didn't go off) and there are green trails around the place.