Case № SITEQ-01Mexico, 1953 · reopened 1973
The Secret of Site Q
An archaeological expedition. A member missing. A black market awakening twenty years too late.
The case
The Secret of Site Q
Set in Mexico in 1953, a member of an expedition team goes missing. Three friends are trying to uncover who it is who may have killed him, working back through their recollections 20 years later.
The plot
The search for Site Q began in earnest in the 1970s when a Yale graduate student noticed a similarity between a number of artefacts and monuments in various collections that were of unknown origin. Purchased on the antiquities black market, these artefacts had to have come from the same source. A repeating snake head glyph and various other features, including some inscriptions which were continued across a variety of monuments held in different collections, prompted the search for what scientists began calling “site Q”. The letter itself standing for ¿qué?, Spanish for which?
Heavy looting of this mysterious site had clearly been going on for some time, with museums and private collectors paying significant sums for stelae, panels, sculptures and codex-style pottery. Tracking down the provenance of these illegally secured artefacts is still underway, but with museums and private collectors easily paying prices of $30,000 – $120,000 for the best preserved relics, few in the local communities are willing to give away their secrets.
Duration
Expect a full story to take around 8–11 hours if done in one sitting.
The envelope contents
What's in the box
We do our best to theme the contents to the story. This means the box will include interesting objects like postcards, maps and other memorabilia. Most of the narrative part of the story is contained in different paper documents which include photographs, personal letters, government documents, telegrams, newspaper clippings and more.
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№ 01The Expedition Memoir
A 72-page typewritten account of the 1953 season, progressed with margin notes and inserts.
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№ 02Field photographs
Contact sheets, loose prints and Polaroid fragments from three cameras.
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№ 03Government correspondence
INAH permits, US embassy cables, private letters marked "confidential".
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№ 04Black market ledger
Sale records, dealer cards and a private auction catalogue.
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№ 05Topographic maps
USGS sheets with expedition track overlays and hand-drawn site references.
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№ 06Telegrams
Nine wire transmissions sent between Chiapas and New Haven.
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№ 07Personal effects
A pressed orchid, a matchbook from the Hotel Humboldt, a pair of dog tags.
Audience & difficulty
Challenging but solveable.
1953–1983
Our games are designed to be challenging but solveable. This story is set in 1953–1983 and includes some interesting ciphers and puzzles. This game is narrative rather than purely puzzle solving in structure, and has an adventure story at its core — you can enjoy the read as well as trying to solve the case. It's designed to be slightly easier as an entry point than some of our other stories.
Ciphers you'll meet
- Letter substitution
- Knock code
- Vigenère
- Grill ciphers
- Column ciphers
From the case
A closer look
Letters of praise
What detectives are saying
“The level of craft here is extraordinary. Each document feels properly aged — you forget you're holding a prop and start reading it like evidence.”
“Spent a long weekend working through Site Q with two friends. Tight pacing, fair ciphers, and an ending that held up when we went back through the letters a second time.”
“A proper case file. Physical materials, good writing, and enough depth to chew on without being obtuse. I'll be recommending this one to the book-club crowd.”
Ready?Case № SITEQ-01
Post me a killing.
Other cases
More on the shelf
Case № INHER-01Cosy
Yorkshire, October 1927
An Inheritance of Murder
British India, 1930s. A fishing-fleet romance, an inheritance that shouldn't exist, and a burnt journal rescued from the fire.
Case № HUMAN-01Classic
Valley of the Kings, Egypt, 1920s
The Curse of Humanrah
A cursed dig in the Valley of the Kings. One archaeologist dead, another vanished, and a funerary text nobody should have opened.
Case № CHING-01Devilish
South China Seas, 1810
The Legend of Ching Shih
South China Seas, 1810. The most successful pirate in history vanished with a fortune. Somebody wrote it all down, and the paper survived.
Before you buy
Common questions
I'm new to Cosykiller — where should I start?
Start with An Inheritance of Murder. It's our gentlest case, built for puzzle-minded beginners — Braille, letter-to-symbol substitutions and one-time cipher pads. The Curse of Humanrah is the next step up with knock codes, Vigenère and occasional folding. The Secret of Site Q sits in the middle — challenging but solvable. The Legend of Ching Shih and Murder at Marlborough House are our advanced cases — do them once you've worked one of the others.
How old do you need to be to play?
Cosykiller is written mainly for adults, but families can participate together. A note of caution: Murder at Marlborough House is set in 1888 Whitechapel and contains graphic descriptions and period drug references — 18+ for that one.
What's inside a Cosykiller box?
It varies by case, but every box contains a cover letter from Fairhall & Brett Inheritance Recovery — the fictional investigators who brief you on the case — followed by the documents, photographs, ciphers, maps and personal effects collected during the investigation. Some cases include dried botanicals, spices, telegrams, theatre programmes and small physical objects. Each case is a complete story in a single box, with the final solution sealed inside. Nothing to download or sign into.
How long does it take to solve a case?
Between six and eleven hours, depending on the case, the number of players, and how much you like to re-read. Most people spread a case over two or three evenings. You can pause whenever you like — put the lid back on, come back next weekend. Nothing expires.
Can I play solo, or do I need a group?
Both work well. Every case is designed to be solvable on your own — no mechanic depends on a second reader. That said, two to four players is where a case shines, because half the fun is arguing civilly about motive over a drink.
I'm stuck on a code — what do I do?
Each case comes with three sealed hint envelopes — open them in order when you get stuck. There's also an online community where other detectives swap ideas (link included with your order). If you'd rather not break a seal, email <a href="mailto:supersleuth@cosykiller.com">supersleuth@cosykiller.com</a> with your case number and the document you're stuck on and we'll help without spoiling.