One day, Ji-Hwan (Cha Tae-Hyun) begins to receive letters from an unidentified person. The letters, containing black-and-white photos of happy children playing, remind Ji-Hwan of his old two friends.

Five years earlier, while Ji-Hwan is taking pictures with his camera, two girls, Soo-In (Son Ye-Jin) and Gyung-Hee (Lee Eun-Ji), walk into the frame. Ji-Hwan falls in love with Soo-In at first sight. He then musters up enough courage to confess his love to her, but she refuses him very politely. Even so, Ji-Hwan doesn't give up and tells them that he wants to be friends the next time they meet. Ever since then, the three of them start a wonderful friendship. They spend time each other always, and consider it the most precious moments of their lives. But they become confused between love and friendship and, finally, Gyung-hee and Soo-in leave him without a trace.

The random letters inspire Ji-Hwan to depart anxiously on a long journey to find his old friends, but while looking for Soo-in and Gyung-hee, he confronts a beautiful yet sad secret.