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.

A girl in Gothic Lolita fashion is murdered during a shopping trip, and the only clue is in her little black dress. A department store terrorist turns an innocent shopper into a walking bomb. Conan's in the midst of mall madness, and even the Men in Black have a whole week's allowance to spend!

Then love is in the air for Detective Santos, and so is a spectacular fireworks show. But the perfect date turns into the perfect crime when his girlfriend becomes the sole witness to a baffling murder...