▁ ▁Plot ▁Park ▁Young - he e ▁is ▁a ▁former ▁national ▁f encing ▁ath lete ▁and ▁currently ▁a ▁detect ive ▁in ▁the ▁n arc ot ics ▁department . ▁She ▁also ▁comes ▁from ▁a ▁family ▁of ▁c ops , ▁from ▁her ▁soon - to - ret ire ▁father ▁to ▁her ▁sib lings ▁and ▁their ▁sp ouses . ▁Han ▁Ch ul - so o ▁is ▁the ▁only ▁son ▁of ▁two ▁not orious ▁crim inals ; ▁his ▁father ▁ste als ▁cultural ▁objects ▁while ▁his ▁mother ▁special izes ▁in ▁document ▁forg ery . ▁ ▁Ch ul - so o ▁and ▁Young - he e ▁fall ▁in ▁love , ▁but ▁when ▁the ▁couple ▁decl ares ▁their ▁intention ▁to ▁get ▁married , ▁both ▁families ▁disapp ro ve . ▁To ▁pla c ate ▁Young - he e ' s ▁father , ▁Ch ul - so o ▁promises ▁that ▁he ▁will ▁pass ▁the ▁police ▁officer ▁exam ▁and ▁become ▁a ▁detect ive ▁like ▁her . ▁He ▁sp ends ▁the ▁next ▁seven ▁years ▁studying ▁and ▁prepar ing ▁for ▁the ▁exam , ▁with ▁Young - he e ▁by ▁his ▁side ▁as ▁support ive ▁girl friend . ▁ ▁As ▁the ▁exam ▁date ▁ne ars , ▁Ch ul - so o ' s ▁parents ▁resort ▁to ▁des perate ▁measures ▁to ▁sab ot age ▁the ▁wed ding ▁and ▁his ▁future ▁in ▁the ▁police ▁force . ▁Meanwhile , ▁Young - he e ▁and ▁her ▁family ▁are ▁ordered ▁to ▁investigate ▁a ▁serial ▁murder ▁case , ▁and ▁using ▁his ▁parents ' ▁expert ise , ▁Ch ul - so o ▁helps