Art Trade: Walled Up

Part of an art trade with [link].

What quality time!

The last beams of light began to fade away as the entrance to the mausoleum was slowly bricked up, making the small room darker, colder and quieter. Inside, Suzie and Kate could hardly struggle any longer as the waste-deep puddle of cement began to harden. Each was bound and gagged with ropes and cloth: a common consequence of too much snooping, especially around old mausoleums! The room was not very large. It held them and the cement, but little else; and once the final brick was put into place, the oxygen would begin to deplete. Say in... 2 hours or so? Their only hope was that someone could find them before then, but was anybody even looking?