Tracking Orcs

South of Garrett’s Junction, the river cuts through a marshy, swampy area for about 20 miles before starting to rise up into the hills.
This swamp is nasty and foul smelling. It is the eastern most reach of an oozing decay leaching out of the side of the volcano housing the dragon. The reek is palpable, and uncomfortably warm, fed by toxic thermal fumes.
Imogene leads you east along the edge of the swamp, trying to skirt the worst of it. Fortunately, the trail you are following seems to have skirted the edge as well. After about 15 miles, the swamp recedes to the south, but the trail you are on continues east up into the hills. Soon, the going is slowed as the hills become more rocky and steep.
Imogene is concerned that the daylight is fading, and urges you to start looking for a good location to make camp for the night. As this is happening, she suddenly stops, and hisses at everyone to get down out of sight. After a few minutes, she points to a high bluff rising ahead. You have reached a broad, flat area surrounded by a high ridge on three sides. As you follow her indication, you just notice a figure moving back from the edge of the ridge. When the figure is out of sight, Imogene cautions you all to stay quiet and hidden. She says there were two orcs on the ridge when she told you to get down, and that there were probably more nearby. She tells you to stay put while she scouts ahead.
After about 10 minutes, she returns to say there is a well hidden cave entrance back to the left from where you are, and a patrol of 4-6 orcs moving around the ridges. She believes that a stealthy approach could gain the entrance undetected. Her concern is that it will be dark in another two hours, and the orcs will be coming out to hunt or do their mischief. From where you are, she doesn’t think you’ll be able to get far enough away to outrun their pursuit, and that once they leave the cave, they will quickly sniff you out.
Her suggestion is to slip in quickly and quietly, and take them by surprise. It’s possible they can be taken unprepared, and overcome in the ensuing confusion.