Ep. 190: Vi presents a third option to Conan regarding Ran's knowledge of his true identity.

190

Vi reveals the gun was a fake and reminds Conan the threat that the Black Organization poses. Since Ran knows Conan's identity, hiding it from her would be cruel but telling her would endanger the lives of everyone around him. Vi gives Conan a third choice that can solve the problem. The next day, Conan attends Ran's play where a Ran and a mysterious black knight are the main characters. During the play a man named Kouhei Mazuda dies from potassium cyanide ingestion. Heiji, disguised as Jimmy , attempts to trick Ran but is discovered by Kirsten. After removing his disguise Heiji concludes that the suspects are Mazuda's friends and the drink vendor. (Source: Wikipedia)