The Double Agent is a Manga/Manhwa/Manhua in english language, Drama series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Sasha becomes a spy after losing everything in the war. She was found by John, the leader of the war and a demon officer with the face of an angel, but...! The spy is caught by the enemy country and becomes a double agent!