Lee Soon-ae is a recently widowed traffic cop who finds herself in over her head after she stops a man for committing a routine traffic violation. Han Yoo-il, the mysterious and charming stranger who was stopped by the ever-diligent Soon-ae, is in fact an international spy, who has come to Korea on a top-secret mission. When Soon-ae accidentally forgets to return Yoo-il's super high-tech spy pen to him, she sets in motion a chain of events that pulls her into the shady world of international espionage. Soon, the Special Operations Unit also becomes involved, including its new chief Kang Joon, who happens to be an old friend of Soon-ae's late husband. Kang Joon, who secretly harbors feelings for Soon-ae, opens an old case surrounding the death of her husband. They uncover secrets involving powerful political and economic figures, which leads to Han Yoo-il.