In 2006, in an ancient city in Transylvania, Romania, a heavy rain fell after lightning split the sky. An uninvited guest who quietly entered the ancient city attacked the sleeping vampire, and it was a mosquito that stabbed the vampire's neck! The mosquito dodged the angry attack of the vampire and disappeared into the night sky. One night in 2006, the blood-sucking mosquito was looking for prey everywhere. The blood vessels of the hot-blooded detective Lo Dolie (played by Kim Soo-ro) were particularly conspicuous. In an instant, the mosquito bit his blood vessels fiercely... From the place where the mosquito bit him, his blood vessels began to turn green rapidly... What will be the fate of Lo Dolie? He is a hot-blooded detective during the day and an irrational detective at night. He is a human during the day and a vampire at night. His extraordinary double life is about to begin...