In the opening scene, Young Peter Quill sits in the waiting room of a hospital, listening to the Awesome Mix tape on his Walkman as his grandpa comes out and gets him so he can say goodbye to his mom. His dying mom gives him a present and tells him he's just like his father. She asks for his hand, but hes too scared to take it. Just then, she dies.
The distraught Peter runs outside and is abducted by a spaceship. Twenty-six years later on the planet Morag, an adult Peter Quill A.K.A. The Starlord (Chris Pratt) is searching for a mysterious Orb. He finds it as Korath (Djimon Hounsou) and his henchmen find Peter. After a shootout, Peter Quill escapes and returns to his ship, the Milano. His partner/mentor Yondu (Michael Rooker) calls and tells him to give him the orb.
Quill decides he's going to sell it on his own. On the Kree Warship, the Dark Aster, Korath reports to Ronan (Lee Pace) that he failed in getting the Orb and that it's in the hands of Quill. Ronan sends assassin Nebula (Karen Gillan) after him, but before she can go, Gamora (Zoe Saldana) volunteers instead. On the planet Xandar, Quill takes the Orb to a buyer and asks what it is because Ronan's goons were after it too.
The buyer suddenly doesn't want anything to do with it and kicks Peter out of his shop. Outside, Gamora jumps Peter and tries to retrieve the Orb herself. Nearby, Rocket Raccoon (voice of Bradley Cooper) and Groot (Vin Diesel) see there's a bounty on Quills head, so they join in the fight. Its not too long before they're all arrested by Nova HQ and sent to a space prison called The Kyln. (Note: Stan Lee has a cameo appearance as an old man on Xandar, chatting up a young lady.)
Pretty much everyone in prison wants to kill Gamora because she's the daughter of Thanos. Drax the Destroyer (Dave Bautista) has a personal vendetta against her because Ronin killed his wife and daughter, so he wants to avenge them by taking the life of one of his family members in return. Gamora explains that shes also against Ronin and was planning on double crossing him. Quill steps in and helps argue in Gamora's favor.
At Sanctuary, Ronin reports to Thanos (Josh Brolin) that Gamora is a traitor. Thanos tells him to take care of her and get the Orb. He also notes that Gamora is his favorite daughter, which pisses of Nebula (his other daughter). Gamora has a plan to sell the Orb to someone else. Quill, Rocket and Groot agree to help and split the reward. Rocket has a plan to escape the prison.