Wales, 1994. Hidden in the trees, a small boy watches as three women - sisters Mary and Iris, and their mother, Kathleen - bury a man in the woods behind their house. He is Fin Delaney, Iris's common-law husband, and the boy vows never to tell what he saw.
Wales, 2018. A violent storm tears a beech tree from the ground, and among its roots the villagers find the skeletal remains of a man who has lain hidden for over two decades. For Mary and Iris, now middle-aged and living quietly in the same house, the past they buried has clawed its way back to the surface - along with the truth about what really happened to Iris's daughter, Angelica, who vanished as a baby and was never seen again.
Dublin, 2018. Across the water, Angela is grieving the death of her adoptive father, Patrick, when her mother Aileen makes a shattering confession: Angela was never formally adopted. She was found abandoned in a field in Kilkenny, wrapped in a shawl embroidered with the name Angelica. Determined to find the mother she never knew, Angela follows a trail of old newspapers and buried violence through Dublin's working-class communities - a trail that leads, inexorably, back to Fin Delaney, and to the women who thought they'd silenced him for good.
As three timelines converge, The Dead Man in the Tree unravels a story of survival, guilt, and the unbreakable, dangerous bonds between mothers and daughters - asking how far a woman will go to protect the people she loves, and what it costs to keep a secret buried for a lifetime.