Kang Dong-woo

Grieving the loss of a best friend she couldn't protect, an ex-bodyguard sets out to fulfill her dear friend's last wish: sweet revenge.

A former serial killer with Alzheimer's fights to protect his daughter from her mysterious boyfriend who may be a serial killer too.

Major crimes unit detective Seong-jin arrests Tae-sung for petty crimes, but shocked to find out that he is the notorious serial killer. However, Seong-jin becomes doubtful of his identity as the serial murder case is investigated.