Park Chang-ho, who has no money and is about to lose his wife, receives a call from the mayor of Gucheon.

Chang-ho is charged with drug abuse and locked up in Gucheon Prison.

Who made Chang-ho, Big Mouse, and why? However, he needs to be recognized as such to protect Go Mi-ho.

Is Chang-ho really Big Mouse? Gong Ji-hoon makes a bet with Chang-ho to find out his true identity.

Ji-hoon approaches Mi-ho to find Seo Jae-yong's thesis. Does Mi-ho know Chang-ho's true identity?

Has Chang-ho been lying to Mi-ho? Mi-ho joins the prison medical volunteer program to meet Chang-ho.

Han Jae-ho warns Chang-ho to stop looking into Jae-yong's thesis. Mi-ho is suddenly attacked.

Chang-ho is in a mental hospital. Will Chang-ho be able to hide his identity in a state of confusion?

Chang-ho stands as an informant in Jae-yong's trial, and Ji-hoon and Choi Jong-rak search for Chang-ho.

Chang-ho calls out Big Mouse, and they respond. An unexpected character turns up at the agreed time.

Chang-ho shifts the power dynamics in the prison to pressure Big Mouse. Choi Do-ha plants a new warden.

The warden plans to use the prison riots to take out Chang-ho and Mi-ho.

The hot-plate restaurant is in ruins. The agitated Chang-ho meets someone unexpected there.

Chang-ho makes a tempting offer to Chairman Kang Sung-geun. Do-ha conspires with Park Yoon-gab to get rid of Chang-ho.

Chang-ho prepares for the full-fledged elections against Do-ha, but Mi-ho's health is in trouble.

The TV debate begins, and Mi-ho almost has the smoking gun that will bring down Do-ha.