Story

The game begins with Lara's home exploding and burning down before a flashback to a week ago, showing Lara on the Mediterranean Sea, looking for Avalon. ​She had hoped to find out what had happened to her mother but instead she discovered Niflheim, a different Norse underworld, as well as one of Thor's gauntlets. She soon learns that Amanda Evert was on her trail and that she had captured Jacqueline Natla. By confronting Natla, Lara also learns that she needs to find Thor's Hammer to open the underworld where her mother is. Natla gives her a lead to begin her search, co-ordinates to the coast of Thailand.

After solving the temple's puzzles in Thailand, Lara doesn't find another piece of Thor's armour but is instead surprised to find that her father had once been here, and reads a message he had left for Natla. Lara deduces that her father found the item but hid it in the Croft family Crypt. ​

Returning back home, she enters her father's secret study buried under Croft Manor. On his desk were several documents, the second of Thor's Gauntlets and a tape recorded message. His message warned Lara that Helheim contained a powerful weapon. As Lara leaves the underground room, an explosion goes off and the manor is now up in flames. The scene catches up with the beginning of the game where Zip tries to shoot Lara, saying that she caused the explosion and had broken into the vault. This makes no sense to her but she decides to check on Alister, however she notices someone lurking in the shadows, a doppelganger, which then kills Alister. Lara battles with her briefly before tending to her friend. He dies, and she decides to continue on with her adventure to end it.

She heads to Mexico and enters another Norse Underworld, Xibalba. Here she battles giant spiders and a new enemy known as Thralls and after solving the riddles, she locates her next armour piece: Thor's Belt. She learns of a Norse sea serpent called Jörmungandr, which can cause the destruction of the world. Next she heads to the Jan Mayen Island, opens the door to Valhalla and collects Thor's Hammer.

With all of Thor's artefacts assembled, she plans to confront Natla; Zip had tracked her down to a ship on the Andaman Sea called Tisiphone, the sister ship to Amanda's 'Megaera'. With Alister's death still on her mind, she angrily questions her for the location of Helheim, and Natla provides it, telling her that she is the only one alive who knows the Ritual of Odin, which is needed in order to open the gates to the Underworld. Lara decides to free her on the condition that when she puts a foot wrong, she will kill her. Natla's co-ordinates point to the Arctic Sea, where Lara has to break a way through the ice. She finds her way to the gate of Helheim and watches on as Natla performs the ritual. Past the gates, she finds her mother, who had been turned into a thrall. Forcing herself to believe that her mother died long ago, she kills her. Natla appears after watching on and delightfully informs her that it was her who had killed Lara's father. She leaves, hoping that the Doppelganger would kill Lara, however Amanda saves her by using the power of her Wraith Stone to throw the Doppelganger over the rocky ledge.

Continuing on, Lara discovers that the Midgard Serpent was actually a metaphor for the network of tectonic ridges that encircle the earth on the ocean floor. The doomsday device stands on the ridge's weakest point, and that when the Serpent would rise up, it would consume the world in fire and ash. By using Thor's belt and Gauntlets, Lara was able to push key stones which then destabilised the device, causing it to topple. Natla tries to hold it up so Lara throws the Hammer at her, hitting her head and knocking her into the eitr below. The cavern begins to crumble and Lara discovers a dais, similar to those that she had seen before in Bolivia and Nepal, and with Amanda's help, they return back to the temple in Nepal. Lara says goodbye to her mother and returns back home.