After the Fifth Doctor discovered a hidden Cyber-bomb in the caves, he told Nyssa and Tegan to escort Scott, Kyle, Marshall and what remained of the troops to the TARDIS to wait. After the Doctor disarmed the bomb, Scott requested that he, Kyle and the troops accompany them to meet whoever placed the bomb in the caves.
The TARDIS landed on a freighter, and the Doctor and Adric ventured outside to have a look round. Growing impatient, Scott took, Marshall, Brooks, Tegan and another trooper outside to search for them, but returned after they became separated from Tegan.
Scott, Marshall and Brooks later left the TARDIS and ventured outside again to go to the bridge to investigate. On the steps leading up to the bridge, Scott told Marshall to stay at the steps to act as a rear-guard. However, Marshall was shot and killed by a Cyberman while Scott was on the bridge. (TV: Earthshock)