Arlo Tyre and Wadie Firestone were assigned by the Alliance to Restore the Republic to travel to the planet Alashan and investigate why they had lost contact with their archaeological station. When they had gotten there, all of the habitation domes had burst from the inside out. When Arlo and Wadie started to walk towards the central habitat dome, Arlo was suddenly shot and killed by an unknown force. Wadie then ran for his Y-wing fighter. When he reached his starfighter, he powered the fighter up and accelerated upward, but was shot out of the sky by the same unknown force that killed Arlo.
The Guardian of Forever.
Because Alliance Command had lost contact with Arlo and Wadie, Luke Skywalker, Leia Organa, Mici Shabandar, and the droids R2-D2 and C-3PO were assigned to investigate their disappearance.