The lock takes less than a minute, the fourth key a close enough fit, assisted with a few bumps from the handle of a screwdriver. The door pushes open into a hallway with off-white tiles laid on the diagonal. Next is an open-plan kitchen and living area, a study nook on the far side of the sofa: small desk, dated laptop, a printout of the invitation sitting atop a neat pile of paperwork.

You are invited to the twenty-year reunion, of the Class of 2000

Deep breath. Don’t get angry. Don’t lose focus.

The laptop whirrs to life, its fan sounding inordinately loud in the silent apartment. No password required, stupidly trusting and naive. Insert the USB, click on install, twenty minutes to completion. Be calm. Be thorough. She won’t be home for hours yet. Plenty of time to check her browsing history, her Facebook page and the rest of the paperwork on the desk. Glimpses into the construct of her life, the friends she holds close, her most secret desires.

Wander into the kitchen, opening and shutting cabinet doors, cataloguing the food she eats, the brand of coffee she prefers. The main bedroom is located down a short corridor. White cotton bedcovers, faux-fur cushions, the book she’s reading - a bestselling thriller - open on the bedside table. Underneath it, another book, larger, sickeningly familiar.

Yearbook of Macquarie High, Class of 2000

Don’t touch it, don’t look at those hateful faces, don’t fall for that fake innocence.

Back to the antiquated laptop. Glare at the screen as it reluctantly grinds through the final stages. Pocket the USB. Switch off the machine. Pause inside the front door, key poised, cap pushed low in case there’s a security camera lurking somewhere. Listen. All clear. Bump, bump, bump goes the screwdriver.

It’s happening. Their shallow lives will be blown apart.

And they’ll be sorry. Finally.

Name: Annabel Moore (School captain)

What you will be remembered for: Not keeping a straight face when Miss Hicks fell up the stage steps on awards night.

Best memories of high school: Year 11 snow excursion.

Worst memories of high school: Double period maths on Fridays. Torture.

What will you be doing ten years from now: Marine biologist.