In The Dig, an asteroid named "Attila" is headed on a collision course for earth, and Astronaut Boston Low comes out of retirement to plant two nuclear devices on Attila to bring it into a more stable orbit. Along with his crew, Dr. Ludger Brink, an Archaeologist; Maggie Robbins, a newspaperwoman; Ken Borden, the pilot; and Cora Miles, the payload specialist; they manage to plant the two devices and set them off.
It's what they find afterwards that gives them the real trouble. Apparently, Attila is not an asteroid, but a spacecraft, that whisks Low, Brink, and Robbins to an alien planet named Cocytus. Unfortunately, it dissolves upon landing, stranding them there. The three of them must unlock the secrets of the planet to get home again, but that means using the alien technology, and finding more about the aliens that may have built Attila.