Entre no mundo virtual de Under A Killing Moon, onde é dezembro de 2042, e você, como Tex Murphy, deve parar as forças do mal antes que elas destruam a humanidade e roubem seu próximo cheque de desemprego. Esta aventura emocionante e hilária é diferente de tudo que você já viu antes. A qualidade gráfica, os personagens fascinantes e críveis e a total liberdade de movimento farão com que você sinta que realmente atravessou a tela e se tornou o personagem principal de um filme de mistério rico e intrigante. Estrelado por Brian Keith, Margot Kidder e Russell Means. Apresenta a voz de James Earl Jones.

Under a Killing Moon se passa em São Francisco após a Terceira Guerra Mundial, em dezembro de 2042. Após os eventos devastadores da guerra nuclear, muitas grandes cidades foram reconstruídas (como é o caso de Nova São Francisco), embora certas áreas ainda permaneçam como eram antes da guerra (como na Velha São Francisco). The war also left another mark on the world: the formation of two classes of citizens. Specifically, some people have developed a natural resistance against radioactivity, and thus are normal or "Norms"—everybody else are Mutants in some form. Tensions between the two groups have risen dramatically and Norms and Mutants usually do not get along. The Mutants are usually forced to live in the run-down areas of cities such as Old San Francisco. Tex Murphy lives on Chandler Avenue in Old San Francisco. Todos os seus amigos são Mutantes, embora ele seja um Norm. In Under a Killing Moon, Tex Murphy, a private investigator, has hit rock bottom. Recently divorced from his wife Sylvia, out of work, low on cash, and living in a rundown part of Old San Francisco, Tex realizes that he has to get his act together. Tex sets out to hunt for work. He finds it quickly once he discovers that the pawnshop across the street from his apartment has been burglarized. Tex quickly solves the case, and feels his luck has begun to change. Then a mysterious woman calling herself Countess Renier, having heard good things about Tex, hires him to find her missing statuette. Everything seems great at first and the Countess is promising to pay Tex more money than he has seen in his life. However, everything quickly goes downhill when Tex finds out about doomsday plot by a deadly cult calling themselves the Brotherhood of Purity.