'20/20' UNRAVELS BIZARRE MYSTERY BEHIND MURDER OF GRANDPARENTS WHO DISAPPEARED WHILE TRYING TO SELL YACHT

'20/20' Airs Friday, Jan. 17 (9:00-11:00 p.m. EST), on ABC

After an early retirement, Tom and Jackie Hawks bought a 55-foot yacht and spent several years enjoying the ocean, using their boat as their primary residence. When they became grandparents, they decided to relocate closer to their grandchild. But as they prepared to sell their yacht to move, they vanished without a trace. A two-hour "20/20" unravels the bizarre mystery surrounding the couple's disappearance, reporting on how authorities collected vital clues; the bone-chilling confession from an accomplice that cracked the case wide open; the surveillance video that led investigators to uncover Skylar and Jennifer Deleon's tragic plot to murder the Hawks; the surprising potential motives behind the murder; and the status of the case now - including updates on Skylar's life on death row. "20/20" airs Friday, Jan. 17 (9:00-11:00 p.m. EST), on ABC.

"20/20" is anchored by David Muir and Amy Robach. David Sloan is senior executive producer.