Conditional Sex: Last One Night.

Mi-young overcomes her painful past and spends sweet time with her co-worker Won-woo. Seok-joon, who broke up with Mi-young after having an affair with Ye-jin, soon breaks up with Ye-jin too because he cannot forget Mi-young. Meanwhile, Ye-jin sees her ex-boyfriend Won-woo with Mi-young and uses a trick to keep them apart.