He also advised Carter to disguise as a ghoul himself; shaving the beard he had allowed to grow (for ghouls have none), wallowing naked in the mould to get the correct surface, and loping in the usual slumping way, with his clothing carried in a bundle as if it were a choice morsel from a tomb. They would reach the city of Gugs—which is coterminous with the whole kingdom—through the proper burrows, emerging in a cemetery not far from the stair-containing Tower of Koth. They must beware, however, of a large cave near the cemetery; for this is the mouth of the vaults of Zin, and the vindictive ghasts are always on watch there murderously for those denizens of the upper abyss who hunt and prey on them. The ghasts try to come out when the Gugs sleep and they attack ghouls as readily as Gugs, for they cannot discriminate. They are very primitive, and eat one another. The Gugs have a sentry at a narrow in the vaults of Zin, but he is often drowsy and is sometimes surprised by a party of ghasts. Though ghasts cannot live in real light, they can endure the grey twilight of the abyss for hours.