Matthew Modine stars as a terminally ill billionaire questioning the existence of the afterlife in TNT's "Proof." To search for answers, he recruits a surgeon, played by Jennifer Beals, who is haunted by the sudden death of her teenage son and her own near-death experience. The deal clincher: She can use his $10-billion fortune for her philanthropic work. Does Modine, an award-winning actor, writer and filmmaker, believe in the afterlife? "I have no idea," he admits. "This moment, this breath is all we have … so I believe in living each moment like there is not going to be another one.