The Time Lords have dispatched the Doctor (in his 2nd incarnation) along with Jamie to a space research station to see Dastari, the Director of Projects, about dissuading two of his scientists from further experimentations on time travel that are rattling the fabric of time. The Doctor is further alarmed over Dastari's latest genetic experiments, boosting the intelligence of a bestial and carnivorous humanoid race called the Androgum. This secondary concern soon proves the greater problem: the Androgum have sided with the Sontarans to take over the station. The station soon falls and the Doctor is captured and tortured. As his life becomes threatened, elsewhere the Doctor (in his 6th incarnation) passes out while on holiday with Peri - his very existence jeopardized.
