The Frog Tsarevna.

The Frog Tsarevna is a Russian folk-tale. Three sons of the tzar, wishing to find wives shoot arrows in different directions: the first son’s arrow fell in the yard of a nobleman, he married the nobleman’s daughter; the second son’s arrow fell on a merchant’s yard, he married the merchant’s daughter; the third son’s arrow flew away to the swamps and was picked up by a frog. Of course it was an enchanted princess. After many dangerous adventures and a series of quests the youngest prince managed to change her into a girl again