Sharma

 was the captain of the spaceship Nandi. The ship was sent to Agni to investigate a meteor shower which they thought had damaged the power station there. In fact, it was a Sontaran invasion. The crew of the Nandi and the workers on Agni were mind controlled and made to work to exhaustion by the Sontarans.

The Fifth Doctor and Nur went to Agni in Nur's private flitter the Garuda. They were attacked by the Nandi, but escaped. In the conflict, a minor explosion freed Sharma from the Sontaran's mind control. He managed to fool them long enough to get away, and found the Doctor and Nur on Agni. After freeing the other enslaved people, he went with the Doctor to negotiate with the Rutans. Once the Doctor got back his TARDIS, which the Sontarans had taken, they fled along with Turlough and Nur. (PROSE: Lords of the Storm)