Empty promises or empty threats?
Like you, I wonder about the endgame here. I can see a range of possibilities.
- Zenon wins. He finishes reprogramming Erin and Mallory and leaves with them. Adrian, Julian and Cherry are left standing in an empty hotel to pick up the pieces. The plot shifts to search and rescue.
- Our Heroes win. Cherry gets rid of the monster, Julian kills the now merely human Zenon, Adrian pisses on the corpse and the women revert to their baseline personalities.
- Mixed victory. Cherry severs the monster's connection to Zenon, turning him back into an elderly normal human, but Erin and Mallory are still reprogrammed. Zenon is forced to ally himself with the SJI gang out of fear of Jakob and winds up living in the basement. Wacky hijinks ensue as the gang tries to prevent Mr. Roper from finding out.
- Mixed victory two. Zenon is killed but his reprogramming sticks. The gang have to figure out how to undo the damage.
More seriously, though, I interpreted the title as a pun: Zenon promising to make Mallory empty. Which does raise a tongue in cheek question: will he get his deposit back if and when he returns his empties?