Do Minjoon, an alien who landed in Korea 400 years ago, discovers that he has three months left on Earth. And that is when he meets Cheon Songyi, the biggest Hallyu star in Korea.

Minjoon embarrasses Songyi in public while she films for a documentary special about her daily life.

Songyi suffers from appendicitis, and forces Minjoon to take her to the hospital. He takes the opportunity to protect her from his premonition.

When an actress dies from an accident, Songyi is immediately the target for blame. She seeks refuge in Minjoon's apartment, uncovering secrets that he'd like to keep buried.

Songyi hides away in Minjoon's apartment after the suspicious death of fellow actress Han Yoora. Prosecutor Yoo Seok begins an investigation to look into whether her death was a suicide or not.

Following the Yoora scandal, Songyi postpones renewing her contract with her management.

As the threats intensify, Songyi turns to Minjoon for help. He slowly becomes more human-like by being around her so often and agrees to be her temporary manager.

Songyi thinks stress is contributing to her "hallucinations" of Minjoon saving her. The investigation intensifies as witnesses to Lee Jaegyeong and Yoora's relationship begin to disappear.

Minjoon gets sick after he shares a kiss with Songyi. Yoo Semi decides to finally meet Minjoon for herself.

Songyi has difficulty dealing with her feelings for Minjoon, who's also trying to distance himself from her and not reveal his true nature to anyone.

Jaegyeong will go at any lengths to get Songyi and Minjoon. Jaegyeong begins to view his brother in a different light.

Songyi refuses to hear what Semi has to say about her savior from 12 years ago. Minjoon recovers from his injuries but realizes that his heart is now broken.

Minjoon does his best to distance himself from Songyi and hold up his end of the deal with Jaegyeong.

When Songyi's wires break while shooting, it's a game to the death with no holds barred between Minjoon and Jaegyeong.

Songyi recovers from her injuries, but Lee Hwigyeong is still in a coma. Minjoon can't stay away from protecting Songyi.

Epilogue

Minjoon and Songyi admit their feelings for one another and start dating, but his departure date looms near.

Hwigyeong won't stop until he finds his sister-in-law and uncovers his brother's dark secrets. Songyi and Minjoon can't deal with the fact that he'll need to leave in a month.

Minjoon's powers weaken as he stays on Earth longer than he should. Hwigyeong discovers his brother's true self, but it will be more difficult than it seems to have him pay for his crimes.

Hwigyeong must find a way to stop Jaegyeong before he himself ends up on his brother's hit list. Songyi discovers the price Minjoon must pay if he stays with her.

With one week left before he leaves, Songyi and Minjoon spend each day as if they had seventy more years left together.

Minjoon's departure is too difficult to bear for Songyi, even three years later.