Doubt

At the scene of Choi Young-min's murder, a woman's necklace is found. Knowing it belonged to his wife, Tae-soo worries it might put Ha-bin at the scene. Later, Tae-soo visits Park Joon-tae after learning that Joon-tae personally knew Choi Min-ah, and the man claiming to be Min-ah's father shows up at Sung-hee's place to question her about the day Min-ah died. Meanwhile, the police station realizes there is a connection with Ha-nin.

Park Joon-tae testifies that he was the only one at the scene when he murdered Choi Young-min. Tae-soo brings Sung-hee to the interrogation room and pushes Park Joon-tae, and he confesses that he killed Song Min-ah to protect Sung-hee. Meanwhile, the police find out whom the necklace found at Choi Young-min's crime scene belonged to.

The violent crimes team identifies Ha-bin as the prime suspect in Choi Young-min's murder. As Captian Oh and the chief order him to step away from the investigation, Tae-soo finds himself in a position without any possible way to make things work. He tries to stop Ha-bin's investigation but soon encounters the shocking truth through Ha-bin's confiscated items.

Tae-soo and Ha-bin find out what really happened to Ji-soo. Tae-soo wants to find the CCTV footage that could be crucial in catching the real culprit, but Ha-bin is against it. Ha-bin thinks it's only right to take revenge on the real culprit for her late mom, but Tae-soo doesn't agree with her.