When Icarus Base is attacked, it's inhabitants are forced to flee through the Stargate. The base was created on a distant planet to take advantage of a powerful energy supply located there. Their goal is to try and determine the purpose of the mysterious ninth symbol of the Stargate which they have never been able to lock in. In going through the Stargate, they are transported not to Earth but onto an very old, apparently uninhabited but huge spacecraft. With the group's commander injured, Lt. Scott and the chief scientist, Dr. Nicholas Rush lead the exploration of the craft. Several areas of the ship have been damaged but it is basically functional. They are able to learn that they are in fact billions of light years from Earth.

With the ship on a collision course, the crew must decide who will stay and who will flee on the shuttle to try and find a habitable planet.

With the situation onboard the Destiny dire, General O'Neill and Home World Command orders Col. Young to execute a high risk plan concocted by the I.O.A. scientists which, in theory, could return the crew to earth.

Chloe behaves in a bizarre way, prompting a search of her quarters, where Lt. Scott finds a journal penned in an alien language. Elsewhere, Eli copes with his mother's medical condition.

Eli and Rush have found a way to identify the location of drone mother ships using the Destiny's long range sensors. The bad news is that the Drones seems to be awaiting them at every possible stop along Destiny's path. They find a temporary solution to neutralize the mother ships but realize that they cannot engage in a major battle every time they need to re-supply. Eli suggest that they use the stasis pods for the crew and jump to the next galaxy, a trip that will take three years. All goes well until they realize that one of the pods has been damaged and one person will have to stay behind in the hopes of fixing the unit in the short time available or die.