Marie is a timid and unassuming viscount's daughter who lives in the shadow of her beautiful half-sister. Her already difficult life collapses when her sister not only steals her fiancé, Prince Maxim, but also uses a curse to transform Marie into an ugly cat. Abandoned and unable to reverse the spell, the newly transformed Marie flees and wanders the city until she collapses from loneliness and hunger.

As she lies helpless in the rain, a mysterious man extends a gentle hand and offers her shelter. This rescuer is none other than the undefeated military duke, a powerful and feared nobleman rumored to be cruel and merciless. Despite his terrifying reputation, Marie has no choice but to accept his protection, and she begins living in his household as a stray cat.

To her surprise, life under the duke's care proves far more comfortable than she ever expected. The man rumored to be heartless shows her unexpected kindness and affection, leaving Marie bewildered as she desperately tries to act like a normal cat while hiding her true identity. As she navigates her new existence, she discovers that the duke is not the monster she once believed him to be. Complications arise when she unexpectedly encounters her ex-fiancé, who had so cruelly discarded her. The story follows Marie as she finds love and strength despite her transformation, ultimately working to reclaim her life while experiencing a reversal of fortune that brings justice to those who wronged her. The narrative blends comedy and romance, beginning with serious themes but evolving into a lighter, more humorous tale as the once-unfortunate heroine discovers happiness in the most unlikely circumstances.