Locks gone.

He took it for granted that the real-estate agent would not come round with prospective tenants.

These doors would take them into the trucking alley, where there were a dozen feasible exits.

There was no way out of the house yard, as the brick wall, ten feet high and running from warehouse to warehouse, was blind.

Now for the trap on the roof.
He climbed the three flights of stairs crisscrossed and festooned with ancient cobwebs.