Milton Carter and his wife Marjorie are protective and loving parents to their three city-born and raised boys. So, when Sam, Ben and Ethan Carter are just beginning to leave their childhoods behind, moving into their teenage years, their father is concerned that they may fall into the wrong company, in the inner-city areas of Bradford, West Yorkshire.
He approaches his friend, the tight-fisted and strangely warm-hearted Jack, who owns a nearby farm, and the two men agree to put the boys to work on Jack's farm, over weekends and during the holidays.
As the summer holidays approach, the boys are made an offer they cannot believe: to look after Jack's farm for two weeks while he goes away, and to camp on the farm of nearby Tom, whom the three brothers really admire and like.
What adventures await the three brothers in this warm and blessed summer, a summer from which they will all emerge changed forever? As the sun warms the hay, so it warms the hearts of the boys and those who begin to develop deep affection for them, like Tom and his family.
Yet, farm life is also brutal, and the ultimate outcome of the summer will be different for all three of the boys... both now and in their adult lives. For one brother, it will push him to change the very world.