Koom Valley? That was where the trolls ambushed the dwarfs, or the dwarfs ambushed the trolls. It was far away and a long time ago. But if he doesn't solve the murder of just one dwarf, Commander Sam Vimes of Ankh-Morpork City Watch is going to see it fought again, right outside his office. He must unravel every clue to find the solution. Oh ... and at six o'clock every day, without fail, he must go home to read WHERE'S MY COW? , with all the right farmyard noises, to his little boy.