When the humans from Maitland's ship, including the First Doctor, Ian Chesterton and Susan Foreman, were invited to the Sense Sphere, the Second Elder had misgivings about the humans' intentions. However, he trusted the First Elder's wisdom and tried to dissuade the City Administrator from speaking against the First Elder's decision. The City Administrator captured the Second Elder and impersonated him in order to destroy the humans.
The Second Elder was killed when he was struck down by the Engineer when he attempted to and succeeded in breaking the firing key for the disintegrator gun, and the City Administrator was later promoted to Second Elder in his place. (TV: The Sensorites)