If you could test your son for a gene that predicts violence, would you do it?

Antonia and Bea are sisters, and doting mothers to their sons. But that is where their similarities end.

Antonia had her son tested to make sure he didn't possess the violent M gene.

Bea refuses to let her son take the test. His life should not be determined by a positive or negative result.

These women will go to any length to protect their sons.

But one of them is hiding a monster.

And there will be fatal consequences for everybody....

PRAISE FOR JAYNE COWIE:

'Nature, nurture, and parenting styles go to war in Jayne Cowie's tense thriller with a twist' Christina Dalcher, Sunday Times bestselling author of VOX

'Original and unsettling' The Sun

'So timely, so relevant and so remarkably written, it's going to live with me for some time to come' John Marrs, #1 bestselling author of The One