Lou and Andy Webb have two young children who are affected by a genetic condition that severely restricts their eyesight. Both 4 year old Harvey and 2 year old Megan suffer from Achromatopsia which means that they can only see in fuzzy black and white. Although they wear special goggles, they find sunlight too bright to be out in. With all their time and energy taken up looking after the children, Lou and Andy haven't been able to make the garden of their terraced house in Tonbridge a more child friendly place and it's currently full of uneven surfaces and a broken down greenhouse. So their friends have asked Alan if he can help.