The Partridge Family (1970)

S2E14 Where Do Mermaids Go?

On their way back from a tour, the Partridges decide to take a break for a picnic along a scenic country road. There, they encounter a free-spirited young woman who loves to travel solo. After spending several hours bonding, she ends up staying at their house for a while. When she eventually departs, she surprises them with a gift of one million dollars.