Bae Hyun-sung, Cha Kang-yoon Make a Risky Deal in 'The Substitute' Trailer

Actors Bae Hyun-sung, Cha Kang-yoon and Park Yoon-ho are stepping into a risky deal in "The Substitute". The TVING original series released its main trailer on Nov. 9.

The trailer centers on Nam Jae-yeop (played by Bae), Kang Geon-tae (Cha) and Ju Hui-dong (Park). The three friends grew up in very different worlds. A single deal is what sets them up against each other.

"The Substitute" follows students getting ready for college admissions who end up caught in a crime because of their own wants and real-life problems. The title points to the suneung, South Korea's national college entrance exam. A choice tied to the test leads somewhere none of them saw coming, consequently, betrayal and conflict follow.

The series reunites director Park So-yeon and writer Choi Soo, the team behind "Pyramid Game."

In the trailer, Geon-tae is a special scholarship student from a low-income family. He has stayed No. 1 in his entire school despite growing up poor. "All I wanted was to go to college," he says about his situation. Later he shouts, "I'm going to live a normal life." But to get the life he wants, he makes a dangerous choice.

Jae-yeop looks like a model student who has everything. Inside, he is angry that he has never been recognized. After he gets slapped in the trailer, it all comes pouring out.

"Because I'm defective," he says. "That's why I always felt broken."

Jae-yeop and Geon-tae learn each other's weak spots and enter into a dangerous deal. When their interests begin to clash, their relationship starts to deteriorate. "This time, it's your turn," Geon-tae warns, hinting at just how far their conflict has escalated.

Hui-dong, Geon-tae's best friend, also gets caught up in the situation. "Like they'd ever take me if I went without Geon-tae," he says, revealing his hurt feelings. He has long looked up to his friend and leaned on him. As tensions rise between Jae-yeop and Geon-tae, Hui-dong starts to change as well.

Near the end of the trailer, a message appears on screen: "Desperation sometimes leads to the worst choices." Then Geon-tae asks, "Can you bet your life on it?"

What deal the three made, and what it will cost each of them, is the question the series is built around.

"The Substitute" premieres exclusively on TVING on Nov. 23.