In the rural village of Mosville, inventor and fire chief Lem Blossom, the son of a pumpkin farmer, falls in love with unsophisticated country girl Mary Griggs. His rival is the worldly Tom Perkins, who is conspiring with her father, Joshua, to corner the pumpkin market. Unable to sell his pumpkins, Pa Blossom turns bootlegger in desperation. Lem learns that the pumpkin crop up north has been destroyed by frost and attempts to corner the market himself by offering a $1,000 prize for the largest pumpkin. When the Griggs home catches fire, Lem saves Mary and Joshua with the aid of his water pump and folding ladder, both of which he invented. Joshua then partners with Lem and approves the young man's betrothal to Mary.