Night of Masks

the long version

Nik Kolherne had a face so cruelly scared and disfigured that he wore a mask to cover it. When he was recruited with a promise of being given a new face, a face which would make a young heir think he was someone else, he was uneasy, but accepted the offer. Then he found out that he was party to a kidnapping for more sinister purposes than he had been told, and he was the only hope of the young heir's survival—if the two of them could survive on a planet veiled in eternal night, swarming with dangerous predators. . . . (from Baen Ebooks)