Meitantei Conan

Synopsis

A person who murders people with a hammer, dubbed "Hammer Man", has been seen escaping to an apartment after assaulting a woman.
Sato and Takagi stalk out the apartment and are later accompanied by Conan, Ran and Sonoko. A home delivery courier, a bike delivery woman, and a pizza deliverer were seen to leave that apartment and were then interrogated. The three reveal they did not meet their client and instead followed notes specified for them; The courier was instructed to leave the package outside the door, the woman was told to pick up the package, and the pizza man was told to leave the pizza on the table and take the money from an envelope. They then realize that while interrogating the three, no one was watching the apartment. They enter the apartment to find a masked man unconscious. Conan removes the mask and notices that the man was knocked unconscious by a hammer and deduces hammer man has impersonated one of three deliverers from before.

(Source: detectiveconanworld)