The second Doctor and Jamie are sent by the Time Lords to space station Camera in order to put a stop to unauthorised time travel experiments being carried out there under the auspices of the head of projects, Dastari.

Dastari has been biologically augmenting Androgums, a race of voracious gourmands, including the chatelaine Chessene who has secretly allied herself with Group Marshal Stike of the Ninth Sontaran Battle Group. The Sontarans raid the station, killing almost all aboard. They capture the second Doctor and take him to Earth, imprisoning him in a hacienda near the Spanish city of Seville. There Dastari, also in league with the Sontarans, plans to dissect him in order to find the Rassilon Imprimature - the symbiotic nuclei within a Time Lord's genes that are the key to time travel.

The sixth Doctor and Peri rescue Jamie from the station and then follow the trail to Spain. The second Doctor is imprinted by Dastari with genes taken from Shockeye, the space station's Androgum chef, but the sixth Doctor rescues him and kills Shockeye.

Chessene destroys the Sontarans and, reverting to base instincts, kills Dastari. She herself then dies through molecular disintegration when she attempts to time travel without the Imprimature.