S1·E680 Cactus Rhapsody

Sonoko, Ran, and Conan are visiting a cacti greenhouse. The sons of the owner interrupt with angry outbursts about being removed from their father's will. The owner explains that he's disappointed in his sons living off his fortune and that he will leave everything to the botanical garden. The security alarm later rings and the son Yasuyuki is found standing over his father's dead body. All clues point to him as the culprit, but the Queen of Deduction reveals that Misa, the housekeeper, killed the owner and used the greenhouse temperature settings to trigger the security alarm to create a time alibi.