When Brigadier Lethbridge-Stewart, his fiancée Sally Wright and nephew Owain Vine embark on a much-needed holiday in New York City, the last thing they expect to find is a puzzling mystery involving coma patients, a stranger from a distant land and a dark menace lurking in the bowels of the city's labyrinthine subway system. Before long, they're battling an ancient evil pursuing a deadly campaign of terror that could bring Manhattan under its control... and the world to its knees.