But when his girlfriend Ji-min (Choi Kang-hee) dies of cancer after he failed to save her on the operating table, he is haunted by her confession that she had unwittingly given a young girl HIV via a contaminated blood transfusion when she was a medical intern years ago and never owned up to her mistake.

The precocious eight-year-old Bom (Seo Shin-ae) is innocently unaware of her condition, and she lives happily with her mother Young-shin (Gong Hyo-jin), and her great-grandfather Mr. Lee (Shin Goo) who's always wandering off and loves choco pie.

Ever since Bom's diagnosis, Young-shin has worked hard to care for her daughter and senile grandfather, keeping a strong face and cheery front despite their poor circumstances and the difficulties of being a single mother.

Young-shin has always been mum about Bom's paternity, but in the small community of Pureun-do, rumors are rife that the father is Choi Seok-hyun (Shin Sung-rok), son of the richest woman (Kang Boo-ja) in town.

At first he mocks the seemingly backward, rural day-to-day life on Pureun-do, but as he observes the Lee family and their constant kindness and selflessness at close quarters, Gi-seo finds himself slowly changing and falling in love with Young-shin.

[3] Compared to its competition in the same timeslot, The Devil (KBS2) and Witch Yoo Hee (SBS), Thank You premiered quietly to little hype or pre-show buzz due to lead actor Jang Hyuk's draft-dodging scandal.