Shen Qin, the seventh princess of Jinwu City, who possesses a stunning appearance, is unwilling to become a tool for maintaining political stability. On the eve of her marriage, she reaches a deal with Seventeen, the owner of a mysterious pawnshop in the city, to exchange her beauty for a brand new identity. But Shen Qin never expected that Seventeen was actually the number one killer in the world, and she happened to exchange faces with this killer. Shen Qin originally thought that she could have a free and easy life, but because of Seventeen's enemies, she fled everywhere, and Seventeen had another purpose and married into the general's mansion with Shen Qin's face. Once again desperate, Shen Qin entered the general's mansion as the maid of the seventh princess and sought shelter with the fake princess Seventeen. The seemingly safe general's mansion was even more dangerous. In order to prevent the secret of their face-changing from being exposed, Shen Qin and Seventeen helped each other to overcome the difficulties. But as Seventeen uncovered the biggest secret in the general's mansion, Shen Qin discovered Seventeen's true identity, and at this time they could no longer return to their respective positions...