Raldon was security chief of Synthesis Station. He welcomed the Eighth Doctor when he arrived onboard Synthesis, not realising that he was not the Time Lord the station was expecting.
He took the Doctor to the War Ollistra when she arrived with Roxita and the Capitol Guard. He later evacuated with the rest of the staff of Synthesis when the power went out and the Vashta Nerada escaped. (AUDIO: Day of the Vashta Nerada)