"You think I'm like Dad."
"I think you have some of his talent and some of his tendency toward... instability."
At twenty-five, Catherine has spent her entire life caring for her brilliant but unhinged mathematician father. Now, following his death, she struggles to come to terms with his legacy. In the old academic's house a proof, a study of prime numbers that could change mathematics forever, seems to have come out of nowhere. But as her grip on reality starts to shake, one question ties the lives of four people:
Who wrote the proof?