Plot

An infamous bounty hunter returns to her childhood home, the chaotic planet Pandora, and forms an unlikely alliance with a team of misfits to find the missing daughter of the most powerful man in the universe.

Lilith (Blanchett), an infamous bounty hunter with a mysterious past, reluctantly returns to her home, Pandora, the most chaotic planet in the galaxy. Her mission is to find the missing daughter of Atlas (Ramírez), the universe's most powerful S.O.B. Lilith forms an unexpected alliance with a ragtag team of misfits - Roland (Hart), a seasoned mercenary on a mission; Tiny Tina (Greenblatt), a feral preteen demolitionist; Krieg (Munteanu), Tina's musclebound protector; Tannis (Curtis), the oddball scientist who's seen it all; and Claptrap (Black), a wiseass robot. Together, these unlikely heroes must battle an alien species and dangerous bandits to uncover one of Pandora's most explosive secrets. The fate of the universe could be in their hands - but they'll be fighting for something more: each other.—Lionsgate

Pandora was once ruled by a powerful and intelligent race of aliens named the Eridians. Even long after the Eridians disappeared, they left behind fragments of their technology and inventions all over the world, which became the foundation of modern human civilization. However, according to a popular legend, the Eridians left their biggest secrets inside a vault that is hidden somewhere on the planet of Pandora. According to a legendary prophecy, only Eridia's daughter could open the vault one day, and nobody else could access it, even if they could find the hidden vault. Despite once being a calm and peaceful planet, Pandora is now home to extreme chaos and violence, all because of various corporations, criminals, and treasure hunters settling on it with only one intention-to find the secret Eridian vault and claim the treasure for themselves.

On a corner of Pandora, as a mercenary soldier named Roland (Kevin Hart) breaks into a high-security prison to rescue a teenage girl named Tiny Tina (Ariana Greenblatt). According to Roland, Tina's father had sent him to rescue the girl and take her back to him, although she finds this story a bit odd. During their escape, they also take along a man named Krieg (Florian Munteanu), who was once affiliated with the bloodthirsty and violent tribe known as the Psychos. Krieg had developed a bond with Tina, becoming almost like an elder brother to her, and so he naturally came along. Although Roland was a member of the Crimson Lance private militia, he now abandons the group and its leader, Commander Knoxx (Janina Gavankar), to travel to Pandora with Tina and Krieg in the hopes of finding the Eridian treasure for himself.

Fifty light-years away, on the distant planet of Promethea, a bounty hunter named Lilith (Cate Blanchett) walks into a bar in the middle of a mission for a few drinks. Holding her bounty hostage still, she sits down at the bar when a few men approach her about a new mission. The extremely rich and influential corporate magnate, Deukalian Atlas (Edgar Ramírez), wants to hire Lilith for a specific mission-to find his missing daughter, Tiny Tina, and bring her back to him unharmed. Although Lilith initially refuses to be a part of this plan, especially since Tina is known to be on the planet of Pandora, she quickly changes her mind after being paid a grand amount for her troubles.

Lilith is frustrated because of two very specific reasons. To begin with, Pandora is considered a wasteland with a high crime rate and no opportunities for a good life whatsoever. Its streets are filled with raiders and criminals of all kinds, along with soldiers of private militias belonging to giant corporations. The entire planet's potential and way of life have been destroyed and taken over by the single desire to find the Eridian vault and the invaluable treasures inside it. Due to the heavy population density, the planet is also a wasteland in the literal sense, as tons of waste from humans and other living beings is dumped everywhere outside of the city. When Lilith first arrives on the planet, the craze about vault hunters becomes apparent, as a bus gives her a ride to her destination, and the driver keeps calling her a vault hunter, suggesting that she is here to find the vault too, just like so many others. Even though she repeatedly refuses to be called so, the driver keeps referring to her as a vault hunter, making her grow frustrated.

However, there is a second, and much bigger reason behind Lilith's hatred towards Pandora, for she was actually born and brought up on this very planet. Lilith's mother (Haley Bennett) was also a vault hunter, who spent her entire life searching for the Eridian vault, and at a critical juncture, she had chosen to prioritize her treasure hunting over being with her daughter. The woman had actually abandoned Lilith when the latter was just eight years old, just so she could roam around the wastelands of Pandora freely and find what she had been looking for. This sense of abandonment had turned into extreme bitterness in Lilith's mind after she grew up. She hates the profession of Vault Hunting and the idea of going in search of treasure vaults, for she knows the flip-side of it-having to leave behind all friends and family.

Lilith wants to keep herself as far away from Pandora and from the irrational craze of finding the vault as possible, but her current mission to find Tiny Tina leads her back to her home planet. Right after landing on the planet, she meets a robot named Claptrap (Jack Black), which follows her around at every instance and tries to make her laugh with its jokes. Claptrap mentions that it had been damaged and abandoned at a dump yard for 36 years. He was programmed to come back to life automatically, right after Lilith returned to Pandora. Claptrap tells Lilith about Tina's last known location on Pandora.

As the bounty hunter tracks down Tina, she is attacked by Tina and Krieg. Lilith has to temporarily join her side to escape the Crimson Lance soldiers led by Knoxx. Lilith realizes that there is more profit in siding with the characters she was considering to be her enemies till now. Tina reveals that she does not want to reunite with her father, and this is why Roland and Krieg were trying so hard to keep her away from every bounty hunter and private militia group. Roland reveals that Tina is one of the keys to the vault and convinced Lilith to join their quest.

Lilith and Claptrap join the gang, too, and they head to a bar run by Mad Moxxi (Gina Gershon), who happens to know Lilith well. As the group heads to a chamber above the bar to meet Moxxi who can help them find the secret vault, it is revealed that Lilith had actually been raised at this very place after she was abandoned by her mother at the age of eight. Roland believes that Dr. Patricia Tannis (Jamie Lee Curtis), an elderly scientist, can help them track down the keys to the Eridian vault and, in the process, lead them to the vault itself.

Tannis was actually the foster mother of Lilith, too, for the latter's mother had left her with the scientist before she went away to find the treasure. However, Lilith did not want to keep in touch with her foster mother after she grew up and left Pandora, resulting in their estranged relationship at present. This is because Tannis always supported her mother's adventures, and she, too, spent a great deal of time looking for the vault, which Lilith found rather irritating. Lilith agrees to put up with Tannis as well, all for the rich bounty she will be paid.

Tiny Tina reveals to Lilith that she does not want to reunite with Atlas, for the man is not really her father. The very existence of Tina in this world is the result of sheer greed for the Eridian treasure, as Deukalian Atlas had literally genetically manufactured her with the sole intention of accessing the treasure. When Atlas and his team had found an old Eridian artifact with some blood on it, they believed it to be the blood of the alien race and carefully extracted the biological remains. Atlas then used this blood to create a human being with Eridian DNA, and this was Tiny Tina. His plan was to let Tina grow up to be a teenager and then use her to open up the secret vault that would lead him to the treasure. Atlas believes that the vault contains advanced technology and weapons, all of which he wants to use to ensure that he and his corporation rule over the world and become the dominant power.

After Tina learned of this horrific truth about her life, that she was created only as a living and breathing key to a legendary vault, she decided to run away from Atlas. This was how she eventually ended up with Roland and Krieg, and now refuses to return to the corporate magnate. Lilith also decides to help the girl from now on, and so she destroys the device with which she was supposed to inform Atlas about Tina's location.

The group is attacked by Knoxx and her forces forcing them to flee. The group had Tina (who was a key) and one of the keys. Tannis knew the location of the 2nd key, which was in a sewer location. They get into an underground warehouse with thousands of boxes, but Lilith is able to find the box which had the key and calls it a lucky guess. They are found by Psychos who live underground and are attacked. The group has to fight their way out of the sewers.

However, Atlas had already been keeping an eye on the group and had been following them too, which is how he is able to reach the vault entrance and force Tina to open it up with her ancestral powers. While the group was retrieving the vault key from the sewer, they used an elevator, which technically Teleported them to a different location, and Tannis stated that this occurrence was proof of Tiny Tina's Eridian roots, for only the alien race could Teleport like that. However, when Tina tries to open up the secret vault, she is unable to do so, as she turns out to not be a real daughter of the Eridians.

The elevator had Teleported the characters because one of them surely had Eridian roots, and this turns out to be Lilith herself. Sometime earlier, Claptrap had played an old recording left behind by her mother, which revealed that the woman actually loved Lilith a lot and did not want to leave her. It was she who had programmed Claptrap to be a companion to Lilith if she ever returned to Pandora, almost as a memory of her lost mother. Lilith's mother had actually found out a grave secret about her identity, that Lilith was actually a daughter of the Eridian race, and she wanted to ensure that nobody else knew about this. Had Lilith's identity been made public, everyone would have fought over her to use her as a key to the vault, and this would have exposed the young girl to great danger. This was why her mother had left her with Tannis, so that Lilith would never find the Eridian vault, but she now has to step up, after all.

When Lilith saw a certain drawing in the holographic memory played by Claptrap, she remembered how she would draw the figure, and her mother would casually tell her about its meaning. Based on these memories, Lilith figured out that she was actually an Eridian goddess named Firehawk, and when Atlas orders Tiny Tina to be killed after she is able to open up the vault, she takes the appearance of the goddess to protect the girl.

Lilith takes on the form of Firehawk and kills most of the enemies, while Atlas, on the other hand, manages to sneak his way towards Tina and hold her captive. He threatens to kill the girl if Lilith does not open the vault door, and so Lilith does not have any other option. However, as the characters go down into the futuristic vault, Lilith once again has the upper hand, since it was her ancestors who had built the place. She uses this opportunity to distract Atlas and Tina, then manages to free herself from his grasp.

At this very moment, a gigantic tentacled monster partly emerges from an opening inside the vault, seemingly upon the wish of Lilith, and drags Atlas down with it. Lilith, meanwhile, decides to stay on at Pandora, as she has found a new family on the planet that she had once hated only because she had misunderstood her mother. Together with Tiny Tina, Roland, Krieg, Tannis, and Claptrap, Lilith forms a group named the Vault Hunters.