Jimmy Kudo, the son of a world-renowned mystery writer, is a high school detective who has cracked the most baffling of cases. One day while on a date with his childhood friend Rachel Moore, Jimmy observes a pair of men in black involved in some shady business. The men capture Jimmy and give him a poisonous substance to rub out their witness. But instead of killing him, it turns him into a little kid Jimmy takes on the pseudonym Conan Edogawa and continues to solve all the difficult cases that come his way. All the while, he's looking for the men in black and the mysterious organization they're with in order to find a cure for his miniature malady.

When a woman dies in a snowboarding accident, Conan senses foul play, but the only evidence he has is the chill up his spine. Maybe a suspicious snowman contains the proof he needs Then, on an old-fashioned cherry blossom viewing trip, Conan and Harley Hartwell stumble upon a haunted shrine. The monks tell a strange story about a room that swallows corpses. Can Conan and Harley prove the culprit isn't an ancient curse, but a very human killer?