Performance Art: Housesitting Edition

It's 2:30 am in our short-term rental. A loud electronic chirp wakes us up. Again. and Again.

Must be the smoke alarm in the hall outside the bedroom. Get up and sure enough, that's where it's coming from.

Get a chair, pull off the cover. Take out the battery. Curse. Go back to bed. And? A loud electronic chirp.

WTF?

Go hunting around the house for another battery. Find some, but they're labeled "best before 8/08".

Put one in anyway. Curse. Go back to bed. And? A loud electronic chirp. WTF?  Maybe it's wired into the house's electrical system.

Get flashlight. Head to basement. Thank goodness the circuits are all labeled in the junction box. Turn off all the upstairs circuits. Curse. Go back to bed. And? Loud electronic chirp.

Mrs. Angus makes me go back downstairs to "see if the switches have turned themselves back on" Now after 3:00 am. Thankfully, the laws of physics still apply and circuit breakers are still off. I turn them back on anyway because that clearly isn't the issue.

As I'm climbing back up the stairs, fantasizing about throwing myself off the roof and getting some sleep at the hospital, I see a small disk-shaped object on top of the books on the bottom row of a bookcase in the hallway where the smoke alarm is located.

It's a Carbon Monoxide monitor. I pick it up and it emits....a loud electronic chirp. I rip off its cover, shake out its batteries and crawl back into bed.

One more such victory and we are lost.