Edelyn Rosehart is a lady of the once-prestigious House Rosehart. After her family's fall, she became a court maid—a role reserved for noble daughters—to restore her house. Recognized for her exceptional memory and observation skills, she is appointed as the personal maid to the youngest princess, Aria.

In her first life, Aria poisoned her own father, Emperor Theodore. She had the unsuspecting Edelyn deliver the tea and fabricated evidence to frame her as the assassin. Just before her execution, Edelyn realized that Aria knew she was innocent but intentionally chose her as a scapegoat.

Upon her death, Edelyn regresses to three months before the assassination. Her primary goal in this life is survival. To avoid the future where she is used and executed, she retraces the assassination plot, seeking to uncover the framing process and the full truth of the incident.

Edelyn only knows the outcome—that Aria killed the Emperor—but remains ignorant of the motive, accomplices, the source of the poison, and the method of fabrication. Initially, Aria appears to be a clear villainess: arrogant, cruel, and willing to use lives for her ends. The reason behind her patricide is gradually revealed through investigation.

The truth is that Emperor Theodore intended to strip Crown Prince Caesar of his authority and place him under house arrest for the sake of 'imperial stability,' while planning to use Aria in a political marriage for a war alliance. Aria decided to kill her father to protect herself and her beloved brother, though this does not justify her choice to sacrifice the innocent Edelyn.