It helps to know the basic premise - she is a surveillance cop undercover. He is a killer and burglar with team. There is a cat and mouse game going on as the cops chase him and his team using memory and observation and cameras. There isn't an explosion a minute so it isn't non stop action. But when the violence happens it is more exciting and scary. Han Hyo Joo is sweet and intelligent looking here. Jung Woo Sung looks quite understated and menacing playing a bad guy for a change.