Detective Conan

Conan and his companions head to a ranch to pick up some chickens for their grade school and get dragged into a dangerous situation. A man claiming to be the ranch owner's younger brother takes Ayumi hostage and locks Conan, Amuro, Mitsuhiko, and Kobayashi in the basement beneath the office. There they find the body of the ranch owner and Kazami Yuya. Conan successfully gets in touch with Haibara and the others above ground, but... What are the objectives of the three men visiting the ranch and the owner's younger brother?