It's Mu Han's 50th birthday. While it's a special day, inevitably, there's a dark cloud hanging overhead as it may be his last birthday. Mu Han is disappointed when Soon Jin doesn't seem to have anything planned for this day. All he wants is to spend some time with Soon Jin and I Deun to commemorate a special day. Meanwhile, unit 401 barges into Mu Han's home looking for her cat.
무한과 순진의 이야기, 그 마지막.
평범한 하루도 특별한 사람과 함께여서 행복한 그들.
아주 특별한 날을 맞이해 특별한 시간을 준비하는데.
죽어가는 시간이자 살아가는 시간을 나누는 두 사람.
그들은 순순히 마지막 작별을 맞이할 수 있을까?