Chul-soo is an intellectually disabled man. Chul-soo learns one day that Saet-byul, a young girl in the hospital, is in fact his daughter. It's not long before Saet-byul escapes the hospital and makes a solo trip to a distant city to celebrate a close pal's birthday in secret. As Chul-soo travels with Saet-byul, the two form a close bond.