From the USA TODAY bestselling author of Behind Every Lie and The Night Olivia Fell comes an unforgettable and heart-wrenching novel about the lengths one woman will go to save her son.

Emma loves her life. She's the mother of a precocious kindergartener, married to her soulmate--a loyal and loving police detective--and has a rewarding career as a doctor at the local hospital.

But everything comes crashing down when her son, Josh, is diagnosed with a rare form of cancer.

Determined to save him, Emma makes the risky decision to sell opioids to fund the life-saving treatment he needs. But when somebody ends up dead, a lethal game of cat and mouse ensues, her own husband leading the chase. With her son's life hanging in the balance, Emma is dragged into the dark world of drugs, lies, and murder. Will the truth catch up to her before she can save Josh?

A timely and moving exploration of a town gripped by the opioid epidemic, and featuring Christina McDonald's signature "complex, emotionally intense" (Publishers Weekly) prose, Do No Harm examines whether the ends ever justify the means...even for a desperate mother.