Middle school sweethearts Jung-woo and Soo-yeon were separated in a horrifying tragedy that continues to weigh down on them as adults.

Now a guilt-ridden detective, Jung-woo has been desperately searching for Soo-yeon for years, but when he crosses paths with her again, she has already become someone else with a new identity.

The show's depiction of the rape of the teenage female protagonist (albeit off screen) caused controversy among viewers and netizens.

[1] Fifteen year old Lee Soo-yeon (Kim So-hyun) is a victim of bullying at school, targeted because her father Lee Tae-soo was a murderer, who was also sentenced to death and subsequently hanged (It was later revealed that her father was in fact falsely accused of the crime he was convicted of and executed for).

Through a series of fated events, she meets Han Jung-woo (Yeo Jin-goo), the son of a chaebol and gangster.

She finally succeeds in moving the money to a Swiss bank with the help of her nurse, Jun Hye-mi.

Wanting to leave Korea safely with Hyung-joon as soon as possible, Hye-mi was ordered to have Jung-woo kidnapped until they can flee out of the country.

Jung-woo's father, wanting to cover up the incident, bribes the kidnappers and the police to fake Soo-yeon's death.

Fourteen years later, Jung-woo (now Park Yoochun) is now a homicide detective and has set his mind on finding Soo-yeon, believing that she is not dead.

Soo-yeon (now Yoon Eun-hye) is now known as Zoey Lou, a rookie fashion designer who appears to have a bright personality, but she still carries the emotional scars of her past inside her.

Meanwhile, Kang Hyung-joon (Yoo Seung-ho), rich with the money his mother took from the Han family, returns to Korea for revenge.

Fourteen years later, Jung-woo, who now is a detective, stumbles upon Zoey Lou, who is remarkably similar to Soo-yeon.

Jung-woo's father fakes her death even though she was rescued by Kang Hyung-joon, a boy she saved from a fire earlier.

Fourteen years later, living under the name of Zoey Lou, she is now a popular rising designer who returns to Korea.

He also lost his past memories (except for those he spent with Soo-yeon) and his intelligence reverted to that of a five-year-old child as a result of huge blood loss from a gunshot wound.

Instead, he burns all the remaining traces of Soo-yeon and allies with the police to fake her death, showing no remorse for this incident.

She was also ostracised like her daughter over her husband's crime, and was later taken in by Kim Sung-ho, a police officer who treats them kindly.

She was devastated till today over her daughter's supposed death and spent the next 14 years raising both Eun-joo and Jung-woo, the latter who runs away from his father's home.

She was the only member of the Han family whom Jung-woo favours and trusts, and still maintains in contact with even after he severed ties with his father.

She was actually killed by Hyung-joon due to him hating her for abusing Soo-yeon, whom he grew to love over the next 14 years he spent with her.

Upon being caught, he falsely confessed that Soo-yeon is dead due to Han Tae-joon bribing him to say so, and subsequently, for rape, murder and kidnapping, Sang-deuk spent the next 14 years in prison before being released.

Shortly after his release, he was found murdered in his home, and his killer was revealed to be Hyung-joon, who thirsted for revenge on behalf of Soo-yeon's rape incident.

An acquaintance of policeman Kim Sung-ho, who later assists Jung-woo to investigate and arrest Harry Borrison (Kang Hyung-joon).

He was convicted of murder and sentenced to death, and subsequently hanged on an unspecified date (latest by 1997 since South Korea did not execute a single prisoner from 1998 onwards).

Tae-soo's fate was mentioned by Kim Sung-ho during his conversation with the teenage Jung-woo while they tried to search for the missing Soo-yeon.

He lent Hyung-joon his French name Harry Borrison to allow him to initiate his revenge plan against Han Tae-joon.

The series was written by Moon Hee-jung, who previously wrote The Last Scandal of My Life and Can You Hear My Heart.

Teenage actors Yeo Jin-goo and Kim So-hyun were first cast as the younger versions of the leading characters, and they appeared in the first four episodes.

They previously played Crown Prince Lee Hwon and Lady Yoon Bo-kyung, respectively, in MBC drama Moon Embracing the Sun.