Mobius is a corporation with unknown motives. With the aim of bringing the world "peace and order", Mobius created the STEM device, which connects human minds to an alternate dimension. In the aftermath of the first game's event, Detective Sebastian Castellanos was dismissed from the police department, and his story was not trusted by anyone. Desperate to find leads, Sebastian becomes frustrated and falls back into drinking, until three years later, his former partner Juli Kidman returns to inform him that his daughter Lily, thought to be dead years ago, is still alive but was captured by Mobius as the test subject for Union, a STEM world created with Lily's brain. Union, which is a reflection of Lily's mind, is extremely unstable, and Sebastian must race against time to rescue her and unravel the conspiracies of Mobius before it collapses. Meanwhile, he must confront different killers who had made their mark in Union, and face his own personal fears and past traumas.