Park Chang Ho, nicknamed "Big Mouth" for making big promises he can’t keep, is a struggling lawyer with a poor track record. Hired by the mayor for his incompetence, he suddenly finds himself framed as the infamous con artist "Big Mouse" and ends up in prison.

His wife, Ko Mi Ho, a determined nurse with a strong will, is set on clearing his name and uncovering the truth behind the case.

Can Ko Mi Ho prove her husband's innocence—or will her search for answers reveal even darker secrets?