Run into the pyramid.

You push past the chief and run into the tunnel, as your captors give chase behind you. A little way in, you hear a grinding noise and look back to see a large stone panel fall from the ceiling, cutting off your pursuers behind it. You must have triggered a pressure plate or something.

You notice that the tunnel is dimly lit by holes in the roof which let in light from high above you. Unable to return past the stone panel, you press on deeper into the pyramid. The tunnel ends at another stone panel which is featureless except for a hole about an inch and a half wide at about waist height. You can't see anything through the hole. Beside the hole is a small carving that looks like a penis. There is also a series of stone steps cut into the left wall, forming a ladder that reaches upwards into the darkness.