Valkyr

Valkyr, or V, is the fictional designer drug at the center of the first Max Payne game, named after the figures of Norse mythology. Max's wife Michelle and newborn daughter Rose were murdered by armed junkies high on it, and three years later Max works undercover inside the Punchinello crime family, which controls the Valkyr trade, while trying to solve their murders. Along the way he breaks up a Valkyr deal and learns that the Russian mobster Vladimir Lem has started a war with the Punchinellos. The drug's trafficking turns out to be part of a larger conspiracy that is somehow tied to the death of Max's family.