Dr. Tom Callaghan graduated college at 14 years of age, he thrives under pressure and attacks a challenge. Although his specialty is science, Dr. Callaghan initially started out as a medic in the Army. He saved several lives in secret skirmishes that took place throughout the world, which is also how he lost his lower left leg.
He then began work as the Army’s top scientist. He was the lead doctor in the “Genesis Experiment” which he predicted would go horribly wrong. Well, you guessed it, it did go horribly wrong, and Dr. Callaghan became the Army’s scapegoat. He was about to be tried for his transgressions, but he made his escape right before the MPs came to arrest him. He has been underground ever since or, as the good doctor likes to say, "I'm hiding in plain sight."