Modern-day espionage thriller

Mission Rogue Protocol

A skyscraper, a hostage situation, a device counting down. Pick the locks one puzzle at a time.

Players: Solo or small teams
Solve time: 60–90 min experienced · up to 3 hours new
Setting: Modern-day espionage thriller
Ages: 14+

£12 VAT included

£1.90 UK shipping, free over £75
Hand-packed in Grimsby
14-day returns

The box

A high-rise has been taken. The techno-terrorists running the operation have built their security around puzzle locks, and they've left a device in the basement counting down. The only way in is to pick the locks off one at a time — in the right order — and meet the final defusal sequence before the timer hits zero.

Slip on the dinner jacket (or the dressing gown — no judgement). The cards are laid out so a small team can divide them up and reconvene with the answers, and a second copy on the table turns it into a head-to-head race. Experienced puzzlers tend to solve it in 60 to 90 minutes; if you're newer to this sort of thing, give yourself an evening.

Two players working through the Mission Rogue Protocol puzzle cards together at a table

Inside the box

What's in the box

Every box is hand-packed in Grimsby. Here's what you'll find when you lift the lid.

Mission briefing card

Sets the scene and points you at the first lock.
A stack of interlocking puzzle cards

Each one a security layer to strip away.
Final defusal sequence

Pieced together from every other card.
Sealed solutions

Don't peek — and yes, we'll know.

Mission Rogue Protocol puzzle mystery box cover

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 Secret of Site Q is the step up: a longer, cross-referencing investigation that's challenging but solvable. Shadows in the Gallery is our most advanced case, layering Playfair, knock code and Caesar ciphers across a post-war art theft — do it 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. Every case is rated 14+ for themes of murder, and Shadows in the Gallery touches on wartime violence and post-war trauma, so we'd steer younger players towards An Inheritance of Murder first.

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 like photographs, ciphers, maps, letters, military archives, telegrams, postcards, and other personal effects collected during the investigation. Some cases include dried botanicals, spices, theatre programmes and small physical objects. Each case is a complete story, with the final solution provided at the end. Nothing to download or sign into.

How long does it take to solve a case?

2-4 hours for our single box solves, and between 6-11 hours for some of our longer games. Length of time also depends on the number of players, and how much you like to re-read and how quick you are at spotting and solving ciphers. 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?

If you become totally stuck on a code, check out the <a href="https://fairhallandbrett.co.uk/" target="_blank" rel="noopener noreferrer">inheritance hunter's website</a> or join the online community where other detectives swap ideas (link included with your order). If you need one on one help then 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 things for you.

All questions

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