Kim Himchan, the professional photographer living in Seoul. Had a troubled past with many mistakes made, but he learned lessons from those mistakes. He lost his beloved wife, and his son had "disappeared".

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Moon Jongup, the mysterious angel who Himchan stumbled upon on a snowy day. As their story goes, secrets that have been locked inside of a safe, can finally be unlocked with a key.

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Is Jongup Himchan's son? Or possibly another angel who fell back down to Earth to work for its own wings?