It's the hottest day of the 1976 heatwave and there's not a breath of fresh air in the labour ward at Lincoln County Hospital. Michelle is having her fourth child, a girl, while beloved husband Dean is sipping a cold pint in the pub. Their little house is already bursting at the seams, but Michelle is sure they'll find a way to stretch their budget and continue life as a blissfully chaotic happy family. They name their new baby Donna.

In the next bed, exhausted and wearing a perfectly impractical lace-trimmed white nightgown, Sylvie has just given birth to her first child at forty and wants to sleep, while her oblivious husband Jeremy hovers and suggests he sketch this 'perfect moment'. The midwife thinks she'll feel more like bonding with her baby when she's had some rest, but Sylvie isn't so sure. She and Jeremy call their daughter Leonora.

When the two little girls are taken to their respective homes, the date of their birth seems to be the only thing to connect them. But one day, years in the future, their paths will cross again when Michelle comes looking for Sylvie--because something happened that blistering hot day, something they both deserve answers to...