Griffelkin is a young devil residing in hell's nursery. On his tenth birthday, he is allowed to spend a day on earth to do as many bad deeds as he can. To aid him in the task, he is given a magic potion that will bring objects to life.
Griffelkin arrives in a city and causes havoc by bringing a statue, a mailbox, and a pair of stone lions to life. He is soon drawn to a human girl about his age. To impress her, he transforms a storeful of toys into a ballet troupe. However, the girl runs home to check on her sick mother, leaving Griffelkin to search for her while being chased by the townspeople and the lions.
Later that evening, Griffelkin finds the girl and her brother mourning their mother's death. Moved by their plight, he secretly uses the last of his potion to bring the mother back to life. As the family is reunited, Griffelkin dissolves in tears.
His day on earth at an end, Griffelkin is summoned back to hell, where his outraged fellow devils place him on trial for his compassionate conduct. Griffelkin is found guilty; as punishment, he is transformed into a human boy and banished from hell.
Griffelkin then returns to the city and again finds the girl and her family, who remember the events only as a bad dream. When the family invites Griffelkin to live with them, he happily accepts.