In 1988, following his mother’s death, a young Peter Quill is abducted from Earth by a group of alien thieves and smugglers called the Ravagers led by Yondu Udonta. In 2014, on the abandoned planet Morag, Quill steals a mysterious orb, but is attacked by forces of the fanatical Kree renegade Ronan the Accuser led by Korath. Although Quill escapes with the Orb, Yondu discovers his theft and issues a bounty for his capture, while Ronan sends the assassin Gamora after the Orb.
When Quill attempts to sell the Orb on Xandar, capital of the Nova Empire, Gamora ambushes him and steals it. A fight ensues, drawing in a pair of bounty hunters: the genetically and cybernetically modified raccoon Rocket, and the tree-like humanoid Groot. Nova Corps officers capture the four, detaining them in the Kyln prison. An inmate there, Drax the Destroyer, attempts to kill Gamora due to her association with the powerful intergalactic warlord, Thanos, and Ronan, who killed his family. Quill convinces Drax that Gamora can bring Ronan to him, though Gamora reveals that she has betrayed Ronan, unwilling to let him use the Orb’s power. Learning that Gamora intends to sell the Orb to the Collector Taneleer Tivan, Quill, Rocket, Groot, and Drax work with her to escape the Kyln in Quill’s ship, the Milano.
Ronan meets with Gamora’s adoptive father, Thanos, to discuss her betrayal. Quill’s group flees to Knowhere, a remote lawless outpost in space built in the giant severed head of a Celestial. A drunken Drax summons Ronan while the rest of the group meets Tivan. Tivan opens the Orb, revealing the Power Stone, an item of immeasurable power that destroys all but the most powerful beings who wield it. Tivan’s slave Carina grabs the Stone, triggering an explosion that engulfs Tivan’s archive. Ronan arrives and easily defeats Drax, while the others flee by ship, pursued by Ronan’s followers and Gamora’s adoptive sister Nebula. Nebula destroys Gamora’s ship, leaving her floating in space, and Ronan’s fighters capture the Orb.