These "tunnels" are well-constructed, with stone floors and wooden beams supporting the ceilings. The construction is certainly not new, though it's not immediately obvious just how old it is. Down the corridor about 20 feet, there are two piles of boxes, which served as the archers' hiding spots. The two archers have stood up and are clearly humans, one of them not much older than Ember, dark haired, tall and gawky, the other grey-bearded and wiry with a scar across one cheek.
Behind the ambush points is a stout wooden door, cracked open right now, but you cannot see far enough in to get much of an idea of what's behind it.
Froak says nervously, "I... do not like the below the ground very much." He peers around Verrian's shoulder and gives a shiver. "I will stay here safe from the storm and watch for anyone coming."