Martin was possessed by the Ancient Lights and began to give highly accurate readings at a local theatre, quickly gaining in popularity. He started a show in which he demonstrated his talents before a live audience. His act caught the attention of the Psychic Channel, which gave him a medium to enact the Ancient Lights' master plan on a nationwide scale. He also took an interest in Sarah Jane Smith, knowing that she had travelled with The Doctor.
The power of the Ancient Lights enabled him to fire energy blasts and exert control over his clients, as well as give accurate information about the past and future.
When his plan of possessing the world and making them "join the circle and the Ancient Lights" was foiled, he said that it was his destiny and disintegrated into space. His fate after that and why he was truly "chosen" remains a mystery.