one day he was driven by great hunger to search amid a deserted camping of some orcs for scraps of food , but some of these returned unawares and took him prisoner , and they tormented him but did not slay him , for their captain seeing his strength , worn though he was with hardships , thought that melko might perchance be pleasured if he was brought before him and might set him to some heavy thrall-work in his mines or in his smithies .