A decade ago, Dr. Frank Carver was reluctantly thrust into a daring rescue mission in outer space. Saving NASA's space shuttle Discovery and her crew, he was hailed a national hero. After years in seclusion coping with the haunting memory of his encounter with the enigmatic alien named 'Sentinel', Carver soon discovers that history does indeed repeat itself as circumstances propel him once again into an adventure far more extraordinary than any he could imagine. This time, Carver, his wife Peggy and former boss Ben Davis discover that the stakes are much higher, with the fate of mankind hanging in the balance.