Grace and Dan Arden are in their forties and have been on the IVF treadmill since the day they got married. Six attempts have yielded no results and with each failure a little piece of their hope dies.
Priya Laghari and her husband Nick Archer are being treated at the same fertility clinic, and while they don't face the same time pressure as the Ardens, the younger couple have their own problems.
Priya is booked for her next IVF cycle the same day that Grace goes in for her final, last-chance embryo transfer. Two weeks later, both women get their results.
A year on, angry and heartbroken, one of the women learns her embryo was implanted in the other's uterus and must make a devastating choice: live a childless life knowing her son is being raised by strangers or seek custody of a baby who has been nurtured and loved by another couple.
Who deserves to be the mother of this child, and what defines parenthood in our current age?
These ethical and legal questions permeate The Mothers, reflecting some of the real-life cases that sparked this book.
The seed for this novel was planted in our very own Women's Weekly offices when feature writer Genevieve Gannon came across some rare but tragic cases of IVF lab mix-ups in America in the late 90s and 2000s.
Each story had different factors influencing the outcomes, but they always boiled down to the same question: who did the baby belong with?
"In one case, hopeful parents discovered they were carrying another couple's baby while they were still pregnant and made the decision that they would hand him over as soon as he was born, but in another example the mix-up wasn't revealed until the baby was 10 months old. The mother was ultimately forced to share custody of her son with strangers," says Genevieve.
"There have been other cases where courts have ruled biological parents have no claim on the babies that carry their DNA. It's all very complicated.
"I couldn't stop thinking about the families caught up in these unimaginable scenarios."
The Mothers has been optioned by Goalpost Television, a division of Goalpost Pictures whose credits include The Sapphires and Top End Wedding.