Harriet, seorang gadis bangsawan berbakat, membuat kesepakatan dengan Old Duke Almandine. Demi menyelamatkan adiknya, ia rela menjadi pengganti ‘mate’ Liam, cucu Old Duke. Liam, adalah Lycan yang ‘mate’nya telah mati sejak lama. Ia sendiri terluka parah dan hanya bisa bangun dari tidurnya saat bulan purnama. Old Duke dan Liam menduga bahwa pria itu akan segera mati tidak lama lagi karena kondisinya yang sedang sekarat. Karena itulah, Old Duke ingin Harriet melahirkan pewaris untuk Keluarga Almandine dari benih Liam, agar keluarga mereka memiliki pemimpin baru. Seiring dengan berlalunya waktu, Harriet sadar ia mencintai suaminya dan mereka pun berusaha menyembuhkan Liam. Apakah Liam berhasil bertahan demi istri dan keluarga yang sangat ia cintai?

Marchioness Harriet Goldlane, a talented noblewoman, made a deal with Old Duke Almandine. To save her younger brother, she was willing to become a substitute for Liam's 'mate', the grandson of the Old Duke. Liam was an Alpha whose 'mate' died long ago. He was severely injured and had been living without a heart for a long time. He could only wake up from his sleep when there was a full moon. The Old Duke and Liam himself guessed that the man would die soon due to his worsening condition. Because of that, Old Duke wanted Harriet to give birth to an heir to the Almandine Family from Liam's seed so that their family would have a new leader. The Alpha's replacement bride would soon find that she was in love with the dying man and now they both wished for a miracle to save Liam's life. Could she fulfill her duty to bear the next Alpha for the Almandines? Would Liam survive to protect his bride and family?