Doctor Who: The Face-Eater (Eighth Doctor Adventures, #18)

When the Doctor and Sam arrive on Proxima II they find a settlement rife with superstition and unrest. The native Proximans are inexplicably dying out, and humans too are being killed in horrific ways, with each corpse's face being stripped bare. Posing as investigators from Earth, the Doctor and Sam must track down the force moving through the dark catacombs beneath Proxima City.