Mr. Iceberg, You Are My Only Cure!

Lillian Hawe, the top assassin of Country A, known as the Shadow Assassin, was poisoned with Heart-devouring Poison during an international summit and was hunted afterwards. She ran into Ethan Thorne, heir to the Thorne family, who was autistic and did not speak, and she kissed him while the hunt was still on. She then learned that the antidote was Ethan himself, who carried a birthmark shaped like a yin-yang fish, and that the cure required intimacy with him. She went back to the Hawe family, took the place of her sister Sissy in the marriage the Hawes had arranged with the Thornes, and married Ethan. In the Thorne house she changed the way he lived and he began to trust her. Feelings grew on both sides. Ethan was kidnapped and Lillian got him back, and after that he began to speak. He decided to cure her. Lillian learned that the cure could cost him his life, and that the alternative was to look for another antidote.