Windfall is a story about twenty suburban neighbors who have been playing the lottery together for years. Suddenly, they win a fortune that amounts to $19,000,000 for each of them.
However, this windfall brings huge problems for many of them. Sean, who is a fugitive after an accident, offers lawyer Zoe half of his share to cash it for him. But Zoe and Sean's past continue to haunt him.
Peter convinces a few others to take control of the town's nearly bankrupt bicycle factory. Meanwhile, Peter's wife Nina betrays him for his partner Cameron, leading to the shattering of Cameron's marriage to Beth over her desire for a child.
Minor Damien leaves home and starts spending big, only to end up married to an illegal Russian gold-digger named Galina, who brings trouble into his life. And to add to the chaos, there is a dispute over one share as Sunny claims it instead of a regular player.