Two strangers have dropped their kids off at a pickup area for a children's camp in Helsinki, Finland. A spark of mutual interest is ignited between the man and woman.

Joo-young tries to call a friend on her birthday after a long time, only to find out that her number is not in use anymore. She spends all day to find her and learns some things she never knew about her lost friend up until now. Soon, the forgotten memory of that day comes back to her.