During The Queen's Decree we wind up in the monastery undercroft and as part of the quest we free a Breton lady, Minone Aloette. How we do this without a key to her cage is another question entirely, but since we apparently have some means of opening the cages please let us also rescue Zhaaruis the Khajiit who is locked up further into the same room.

Justice for Zhaaruis!

EDIT: I think possibly Minone is supposed to let him out, but she just stands outside his cage for a second and then runs off.