A long and devastating war has left the land of Eris in ruins.

Out of the ashes rose a group of powerful and corrupted individuals, all vying for control of the land. These people are referred to as the Pravi, and they will stop at nothing to seize control of Eris. They play dirty, killing potential enemies to ensure that their route to power is not disrupted.

The condition of Eris worsened over the next few years. No one knew who to trust. Friends were stabbing each other in the back, and families were being torn apart. Food and shelter were scarce, and commoners would do anything to put bread on the table.

Cho Seoyoon was born at the of the war, and her parents struggled to raise her along with an older brother and sister. When she was 14, her parents and siblings were killed in a bombing, leaving her to fend for herself. At a young age she learned to not trust anyone in order to survive.

Now, Seoyoon is 20. Since the death of her family, she made herself strong. She seeks revenge against the Pravi, the cause of her loved ones' deaths.

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Somewhere across the land, another group is stirring. They are very different from the Pravi. These individuals are known as Salus, and they secretly work to get rid of Pravi. They lie low because they don't want to be targeted by the Pravi, but they have their own way of fighting back. They recruit young members and train them to be skilled assassins. These assassins will be a part of the Salus's special army.

Byun Baekhyun's parents were a part of the original Sali, and when he was born, he was immediately volunteered by his parents to receive training. He and his best friend Park Chanyeol went through all the ups and downs together, and when they turned 20, they became official members of the Salus's army. They are smooth, quick, and skilled with weapons, while being intelligent at the same time.

Now they are 22. They are experienced and have taken down many high ranking Pravus officials without being caught. They are going on their most dangerous mission yet. The Pravi haven't been doing anything lately, and the Sali suspect that they are working on their next major plan. Baekhyun and Chanyeol are to infiltrate one of the many Pravus headquarters and find out what the Pravi are going to do next.

Somewhere else, Cho Seoyoon is also planning to enter the same headquarters.

What will happen when they meet? They both think the other is a Pravus. What will happen when they feel an undeniable attraction towards each other?