Mysteries of Angels and Demons talks to theologians and occult experts and examines cultural and sociological perceptions of demons and angels in religion and spirituality. It also looks at eyewitness testimony from several people who claim to have had encounters with angels and demons.

Joseon's top detective Kim Min attempts to track down those responsible for circulating massive amounts of counterfeit silver bullion in Joseon. He also tries to find the missing sibling of a young girl.

Post-war South Korea in 1953, Heo Sam-Gwan (Ha Jung-Woo) works on a construction site and helps his uncle to farm. The guys in his village can't get married, until they are able to sell their own blood. By selling their blood, they prove they are in healthy condition and are able to make a lot of money. One day, Heo Sam-Gwan sees Heo Ok-Ran (Ha Ji-Won). She's the most beautiful woman in the village, but she is already dating wealthy playboy Ha So-Yong. Heo Sam-Gwan decides that he will marry Heo Ok-Ran. He sells his blood and makes enough money to marry her. 11 years later, Heo Sam-Gwan and Heo Ok-Ran are happily married and have three sons, but a rumor spreads around the village that Heo Sam-Gwan isn't the real father of their eldest son.