It's slow going, especially after you get out of the glow of Dieter's light. Infravision might help with heat sources but the bridge emits none, so Furuk's vision is severely muted and Grimes is effectively blind.
You shuffle along, holding the rope "railing" and trying to be quiet and stealthy. The bridge dips, as rope bridges do, and is starting to ascend as you pass the halfway point, when the half-orc sees something ahead. There are blobs of heat that go in and out of vision, as if some creatures are walking back and forth behind large objects.
I assume you stop to asses and take some...
Actions?