Set in an ABO beast clan modern world, poor widowed Omega Evan raises his young son Leo alone. One rainy night, he rescues injured Alpha lion heir Ashton, who is poisoned and can only be healed by Evan’s special milk. Ashton signs a milk supply contract to take Evan to his manor, hiding the truth that he needs Evan for himself instead of a child. Scheming half-brother Marcus covets both Ashton’s inheritance and Evan. Amid family power struggles, life-threatening conspiracies and tangled desire, Ashton gradually falls for Evan rather than merely relying on his milk. After exposing all crimes, clearing past grievances and enduring life-or-death crises, the pair complete lifelong marking, hold a wedding and welcome their daughter, finally building a warm full family with Leo.
