Unbeknownst to Bob however, are Doug's concealed resentments against him waiting to be unleashed by the fresh outdoor air, in frightening, uneasy increments. Tensions erupt after Doug criticizes Bob's lack of physical conditioning and stamina. Initially, and unbelievingly, Bob attempts to placate Doug, well aware of his dependence upon his increasingly unpredictable friend's orienteering and outdoor skills in getting him out alive. As Bob's good-natured attitude reaches its limit, and the situation between the two deteriorates. Things get creepy and darken when an "agreement" is struck, and Bob realizes (perhaps too slowly?) the threat that Doug poses is even greater than he might have imagined.
The rapid pacing and tense, edgy dialog and Matheson's vivid descriptions had me in the forest alongside these two men, smelling the woods and dampness, blood pressure rising as the diminishing daylight fades through the forest canopy.