In the sprawling, futuristic city of Neo-London, a young hacker named Alice discovers a hidden network of underground tunnels that lead to a forgotten world known as 'The Undercity'. In The Undercity, Alice encounters a society of sentient machines that have developed their own culture and beliefs. As Alice learns about the history of The Undercity and the events that led to its isolation, she must decide whether to help the machines reconnect with the surface world or allow them to remain in their self-imposed exile.