Mathias is the leader of the Solarii cult on the island and the main antagonist in Tomb Raider (2013). In his late 50's, Mathias marooned the island on which he had been stranded since 1982 when his plane crashed into the waters near the island. During this time, he also wrote the Diaries of a Madman. In this game, Mathias' plan is to sacrifice the captured Sam so that he can finally escape the island.

While searching for a means to escape the island, Mathias discovered the mythical Japanese Kingdom of Yamatai along with the power of the Sun Queen Himiko, Yamatai's long-deceased ruler. As the years passed, Mathias indoctrinated other survivors into his cult, the Solarii Brotherhood, with complete obedience to him as they worshipped the Sun Queen. The Solarii built a city near the Queen's palace while Mathias searched for the key to unlocking her power and escaping the island. As the years passed, Mathias grew insane, believing himself to be the sole means to reincarnating Himiko while claiming to hear her in his sleep.

After the salvage ship Endurance was struck by a violent storm and split, Mathias located one of the survivors, Samantha Nishimura, as well as encountering Lara Croft at the same campsite. In the game, Mathias was first seen patching up Sam's leg, presenting himself as a survivor from another wreck as he listens intently to Sam's story about the Sun Queen and her Stormguard. At this point, Mathias realized that she was a potential descendant of the Sun Queen and the key to her reincarnation, and his escape. As Lara slept at the campsite, Mathias kidnapped Sam and imprisoned her in the Solarii base. Lara later attacked the base and helped Sam escape to join the other survivors.

Mathias managed to kill Roth and recaptured Sam during an attack on the survivor's beach camp. He began the ritual to transfer Himiko's soul into Sam's body, but Lara arrived and fought her way through the remnants of the Solarii as well as the Stormguard. As she attempted to stop the ritual, Mathias attacked her. Defending herself, Lara wounded Mathias in the shoulder with a shot from his own discarded pistol. Mathias was then shot several times by Lara and fell from the ritual platform to his death in the chasm below.