A company president who hired Kogoro to protect him is murdered along with his secretary and the investigation reveals that there's more to the case than meets the eye.
Conan and the Detective Boys stumble upon Takagi and Chiba on a stakeout where they are watching a ransom hand off to a kidnapper who has taken a 5 year old child, hoping to arrest the kidnapper.
Kogoro accompanies a woman who hires him to help her track down a stolen brooch when the robber sends her clues in letters. Along the way, they are set upon by attempted murders and suspicious accidents.
Sato and Takagi seek help from Kogoro when they investigate the work of a criminal mastermind. When they discover that he has apparently arranged to have someone killed by explosion, they rush to identify the target and stop it.