Cosykiller is an interactive murder mystery subscription box for the armchair sleuth

Use code MOMSDAY at checkout to get a special discount
Plans as low as $36.67 / month
Product Overview
  • We ship on the 1st and 14th day of each month. For USA and overseas territories: boxes should arrive within 7-10 days. We hold back UK orders and ship those 5-7 days later so that the monthly cohort each receives their box at roughly the same time. All boxes should reach their destination within 7-10 days.
  • Ships worldwide from United Kingdom
  • Subscriptions automatically renew. Cancel anytime
Immerse yourself in the story and find the killer
Always fancied you could crack a cold case? Now you can find out with a Cosykiller subscription box. Each storyline lasts a year. The box is delivered directly to your door and packed with vintage memorabilia, keepsakes and intrigue. There are puzzles, ciphers, suspects, back stories and false leads. It's difficult and requires tenacity.
  • Work on your own or in a small "detective team" as the boxes arrive
  • Work at your own pace, or ask for hints from the private facebook group
  • Features vintage memorabilia, coherant storylines, replica items, keepsakes
  • Solve a murder from the comfort of your own armchair!
  • Each letter accompanying the box is personalized to the customer - which makes it a great gift item.

Subscriber ReviewsReviews

Write a Review

Murder, mystery, intrigue

by Rebecca P., Sep 03, 2018

Cosy Killer is by far the best murder mystery subscription box. If you are looking for an engaging experience filled with authentic characters, a story with multiple interwoven plot lines, puzzles that are organically entwined within the narrative which serve to enhance the whole experience then this is it. The excellent skills of the CosyKiller team encourage an inevitable emotional investment in the characters. While you know that you are investigating the death and whereabouts of Marie, there is a point in Box 9 where you decode a tricky artifact, with every letter decoded my heart ached a little as I could predict what the next letter would be.

If you want an experience like no other I have encountered, one that will keep you puzzling and that keeps you coming back for more - then Cosy Killer is the only subscription box out there.

Treat yourself - you won't regret it

|Report abuse

Varied, multi-puzzle, longform narrative

by Craig J., Aug 30, 2018

Let's get the downside out of the way first - CosyKiller is a year-long subscription. Telling one story over twelve monthly boxes, it's some commitment of money and time.


What it gives you back for that subscription is unsurpassed in terms of mystery subscription boxes. There are no phone numbers to call that might end up disconnected after a few months, there are no websites to visit that might be taken offline at no notice, everything you need is there in the boxes.

And what boxes they are - one month you might get a 128 page diary/journal containing two obvious ciphers and one very well hidden one. You might get twelve to sixteen letters from one character to another, including drawings and birthday or christmas cards. You might get clay artifacts, or death certificates, or shipping manifests, or telegrams, or....

You can read something in box 8 that reminds you of something in box 1 to find an inconsistency in testimony that feeds into the final solution - you can find ciphers in early boxes that are made more explicit later on, but still solvable at that early stage.

The commitment is huge, but the project is major league, satisfying, intelligent, interesting and thoroughly recommended.

|Report abuse


by Lisa S., Aug 29, 2018

I am only three episodes in but the storyline is awesome and very gripping. I didn’t want to stop reading! You get very authentic items and they pay close attention to detail. Very impressed!

|Report abuse


Have a question?

Ask the community and get help from thousands of informed subscribers.

Subscribe Now