Romana got out her sonic screwdriver, to use as a bit of a torch. And to take a few readings. Nothing much useful came up, but the corridor was brighter.
It wound around, to a lift.
"Ok, I'm just going to call that a dead end, the Master said.
"And I'm done playing by his rules," the Doctor said.
"Obliterate a line for us, sweetheart?" the Master called over his shoulder.
"On it!" the Doctor said cheerfully, taking what everyone but Romana would recognize as Jack's sonic blaster out of his pocket, and zapping a square out of the wall to their right.