Three sisters, who only have each other and never enough money, get entangled in a conspiracy involving the rich and powerful.

A woman puts everything on the line to achieve her goal of being able to move into a luxury penthouse in the Gangnam District. In the process, she gradually finds herself turning into a monster.

Kim Min Gyu is the largest shareholder of a financial company. He suffers from a "human allergy", preventing him from normal interactions with other people. He becomes interested in a robotic project named Aji 3 created by the Santa Maria robotic team. The team is headed by Hong Baek Gyeon, inventor of Aji 3 and world-renowned robotics professor. He modeled Aji 3 after his ex-girlfriend, Jo Ji A, a struggling inventor that also works as a personal shopper to make ends meet. Just when Min Gyu wants to test the robot, an accident causes the malfunction of the robot's battery. Baek Gyeon begs Ji A to take the place of Aji 3 and pretend to be the robot so they can get funding from Min Gyu. But Aji 3 becomes the closest thing that the lonely Min Gyu has to real contact with another person.

Kim Min Gyu has wealth and success, but lives an isolated life due to his allergy of people. He then meets and falls in love with a girl who is pretending to be a robot for her ex-boyfriend, a genius robots professor.