Sister

In a desperate attempt to pay for her younger sister's surgery, Hae-ran teams up with Tae-soo to kidnap her half-sister So-jin, who is unaware of their plan. So-jin wakes up in a strange, confined place where Hae-ran and Tae-soo demand a large ransom from her wealthy father. When So-jin realizes that Hae-ran is her half-sister and one of her captors, she forms a cautious alliance with her, which complicates the situation. Together, they navigate the dangerous dynamics with Tae-soo, as So-jin begins to plan a way to fight back against him.