KT-28’s, or Katies, as they are known on the street, are a psychoactive drug from the graphic novel Watchmen by Alan Moore and Dave Gibbons. The effects of this drug are never made clear in the book, only that it is a popular and addictive street drug with the ‘Knot-Tops’ of New York – a curious coincidence, given the drug’s name.

However, in an apparently unrelated section of the book, Dr Manhattan mentions that he can synthesize lithium in limitless amounts, leading to a number of scientific advances based on cheap, abundant lithium.

On that basis, it is likely that this otherwise unknown drug is also a lithium derivative – and indeed, lithium has a long history as a drug used in psychiatric treatments, making it a likely choice. Based on the name of the drug, which sounds more like an abbreviated chemical formula than anything street, it’s likely that KT-28 is a drug with a legitimate psychiatric use that finds its way to the streets illicitly.