You shake the bars: "Hey, guard, I've lost my memories!  Do you know
   who I am?  Do I ask this a lot?"
   The guard turns to look at you, begins saying "You ...!", then suddenly
   vanishes in a burst of dense dust.  Their sword, keys and garments drop
   to the ground with loud "Clang!"s.  Some of the dust blows down the
   hallway, other drifts over the torches and strengthens their flames
   amidst sparks.
   In the distance, you hear echoes: "Hey!"  "What was that?" "Better go
   check it out ..."
   What do you do?
   > take keys