In the Pilot episode they discover Lukes frozen body in a glacier in Fairbanks Alaska. When he is unthawed he returns to his natural living state -- exactly the same age as when he froze - it was like time stood still. The government alerts Lukes son (now in his 60s) that his dad is alive -- and technically younger than him. They then return Luke home and all chaos ensues as Luke tries to adjust to the 20th century.
