The Bad Seed (1956 film)

The Bad Seed is a 1956 American horrorthriller film with elements of film noir directed by Mervyn LeRoy and starring Nancy Kelly, Patty McCormack, Henry Jones, and Eileen Heckart.

On her piano, eight year old Rhoda Penmark Patty McCormack plays the French song Au clair de la lune, while her father William Hopper says his goodbyes to her and his wife, Christine Nancy Kelly, as he goes away on military duty. Their neighbor and landlord, Monica Breedlove Evelyn Varden, comes in with a present for Rhoda a locket. Rhoda, looking pristine and proper in her perfect pinafore dress and long blonde pigtails, thanks Monica for the gift. She then tap dances on the hard floor. Monica notices Rhodas tap shoes, and Rhoda says that adding the taps to the shoes was her own idea. They then discuss a penmanship medal competition that Rhoda lost to her schoolmate, Claude Daigle Monica speaks of it as a childish disappointment, but Rhodas face darkens with fury. Christine and Rhoda leave for the school picnic at a nearby lake.Later, Christine is having lunch with Monica and friends when they learn on the radio that a child has drowned in the lake where Rhodas school was having their picnic. Christine worries that the drowned child could be her daughter, but a followup report indicates that it was Rhodas schoolmate, Claude, the penmanship winner. Relieved that Rhoda is alive, Christine worries that her daughter might be traumatized by seeing the boys corpse. When Rhoda returns, however, she is unfazed by the incident and goes about her daily activities. ........

Source: Wikipedia