Cristina knows all about boundaries. As a therapist, it is vital that she keeps her clients at a professional distance.

Enter new client Leon: a handsome, charming, affluent photographer with a secret. He was the lover of one of Cristina's recently deceased clients, Michelle, who had come to Cristina for therapy to help her choose between Leon and her husband.

Once Leon's secret is out, Cristina commits to guiding him through his grief and ignoring her own growing attraction. But up against sophisticated, attentive, insistent Leon, her boundaries blur and then collapse, and the two set out on their own idyllic love affair.

But why does Leon switch so quickly from charm to criticism, attentiveness to distance? Can anyone truly be as perfect as he paints his beloved Michelle to have been, and what is hidden inside of her off-limits therapy file?

With so many lies unravelling, is Leon really who he says he is?

For fans of You, Before I Go to Sleep and Obsession, Her Little Secret is an utterly chilling new psychological thriller about obsessive love and the danger of crossing lines.