When a long-anticipated holiday takes an unexpected turn...

Aussie farm girl Matilda Moore kicks off her dream trip to London by flat-sitting for her childhood friend. But London is daunting, crowded and noisy, and that's before Tilly finds a baby on the doorstep. There's a note attached: "Henry, if you're reading this, please know the worst has happened."

Probability expert Henry Church has finally returned home to Wirralong, Australia to see his grandparents when he gets a phone call from Tilly that breaks every statistical analysis. The probability of him being the father is marginal. Plus, he knows nothing about caring for a baby. Emotions and socializing are even bigger mysteries. He begs Tilly for help—can she cut her holiday short and bring the baby to Wirralong?

Tilly will do almost anything for her childhood best friend, but falling in love with him and his motherless baby is an emphatic no. Out of the question. Or is it?