Cosykiller — for the armchair sleuth

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Six to eleven hours of mystery per box. Hand-packed period detail inside, sealed answer at the bottom, no app to download. Filter by difficulty or theme, or tell us what you're after and we'll pick the right one for you.

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New to Cosykiller? Start with An Inheritance of Murder — it's our gentlest case, designed for first-time sleuths. Work your way up to Murder at Marlborough House once you've earned it.

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Showing 6 of 6 cases

Difficulty
Theme
Marlborough House seen through a rain-streaked window at dusk, a silhouetted hand pressed to the glass

Case № MARL-01Devilish

Whitechapel, London, autumn 1888

Murder at Marlborough House

Victorian Whitechapel, 1888. Not the one you're thinking of — but the same streets, the same fog, the same kind of quiet cruelty.

£109 Open the case
A vintage Post Office telegram reading "The Hidden Listener" with the Cosykiller stamp affixed

Case № HIDDEN-01Devilish

Interwar Britain, 1930s

The Hidden Listener

An interwar radio operator. A coded knitting pattern. And somebody in the room who shouldn't have been listening.

£99 Open the case
The Site Q case file laid out on a dark wooden table — National Geographic article, army-green hurricane lamp, Mayan glyphs and expedition correspondence

Case № SITEQ-01Classic

Mexico, 1953 · reopened 1973

The Secret of Site Q

An archaeological expedition. A member missing. A black market awakening twenty years too late.

£135 £119 Open the case
The Legend of Ching Shih — South China Seas pirate-era mystery placeholder

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.

£109 Open the case
A misty view of the Taj Mahal at dusk — the Indian setting for An Inheritance of Murder Start here

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.

£89 Open the case
A granite pharaoh statue lit from below against a dim museum wall — the opening of The Curse of Humanrah case file

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.

£99 Open the case

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