William and Donna were born on the same day, in the same Dublin maternity hospital. But there the similarities end.
Will grows up in an affluent suburb and struggles to balance what he wants with what will keep his overbearing mother happy. Across the city, Donna, raised by her older sister, often wonders what life would be like without her troubled mother around.
Over the years, Donna and Will almost meet many times, but something - fate? - keeps them apart.
Then tragedy strikes for each of them.
As Will tries to come to terms with a life-shattering event, he decides to travel the world in the hope of finding happiness. Donna, now alone in the world, makes plans to leave Dublin to fulfil a life-long dream.
More than 10,000 miles from home, they finally meet. And they know nothing will ever be the same.
When a terrible disaster separates them, Will and Donna find they can't stop thinking about each other, about what might have been.
Perhaps fate has plans for them still, and all hope is not lost ...