Arugs backs Lyra's advice - the tunnel needs to be barred and guarded. He'll offer to collapse the tunnels, if they'd rather be on the safe side. Moving a few tons of rubble is considerable more trouble than overpowering a few guards.
The mayor gives Argus' suggestion some thought and then accedes, though urges you to collapse it at the far end of the tunnel.
Once that's done, you begin making your way to the orcs' camp described by Yvogga at the base of a nearby bluff.
Some scouting will be in order. "If nothing else we can get a message back to Arwyll stead about the forces arrayed."
Lyra (and Olive most likely) will take point on that part.
"Yeah, daytime is best. We can't sneak up on them anyway."
Lyra and Olive creep as close to the camp as they dare, where they see a group of six orcs dicing around a campfire; for a second, it appears one of them spots Olive, but he shrugs it off a moment later, apparently assuming it was just the wind or a falling leaf.
A cave opens up behind the orcs, and itt looks like four humans, presumably Terrin's scouts, are held behind a fence of upturned logs, tangled wire, and cruel metal barbs nearby.