The house entered a binding agreement, on their own accord, and now, after they decided they no longer need the assistance of lawful dwelling shadow folk, they want to have the party kill the current contract holders.
The end fight is with a monk npc. A lawful, rule abiding individual that is only seeking what was already agreed upon to be his reward for his labors. which means hes justly acting under the boundaries set forth on a predicated consigned upon arrangement of both joining parties (the house and the shadow folk).
but now the house wants to be free of their oppressors.
so they hire a group of adventurers that are strictly a 'no evil' policy group to save them, kill the parties involved, burn the contract, and cover up and involvement they may have had with them