In snowy Helsinki, Finland, two strangers—Sang-min (Jeon Do-yeon) and Ki-hong (Gong Yoo)—meet while dropping their children off at a special needs camp. Bound by shared isolation and heavy domestic burdens, they take a trip together to the campsite. When a heavy snowstorm traps them, they spend a passionate, anonymous night together at an isolated cabin before parting ways without exchanging names. Months later back in Seoul, Ki-hong tracks Sang-min down at her boutique. Their suppressed longing reignites into an intense, clandestine extramarital affair in South Korea. As their emotional attachment deepens, Sang-min builds the courage to leave her husband, but Ki-hong ultimately chooses family duty over his feelings, leaving both trapped in painful resolution.