Sunho falls off the school building. Sunho's parents are devastated to see their boy unconscious in the hospital. Meanwhile, Sunho's friends secretly delete a video playing the "Avengers Game" on their phones before meeting with the detective on Sunho's case.

Daegil is mysteriously killed from a hit-and-run accident on his way to meet Moojin to tell him the truth. Joonha finds out that Daegil was spotted at the subway station retrieving something from the lockers. Meanwhile, it suddenly occurs to Moojin that Daegil gave them a cactus as a gift before he died.