It only takes a second to change a family forever. Why do you love your child? Is it because they're funny, kind or creative? Or is it simply because they're yours? Sarah and Phil love both their children. The couple have the same hopes and aspirations as any parent. But their expectations are shattered when they discover that their beloved Lauren has been born with a tiny genetic glitch that will shape her future, and theirs, irrevocably. Over time the family adapt and even thrive. Then one day a blood test result changes everything. Lauren is not Phil's child. Suddenly, their precious family is on the brink of destruction. But the truth they face is far more complex than infidelity.