Team Nicholas re-charge at an ocean-side grilled eel restaurant while K's team visit a night market in Busan and try various street food. Team K meets a hurdle as a member is unable to participate and they must re-practice with new formations and positions days before the final performance. Nicholas' team show a powerful performance, while Taki's team challenge a performance involving modern dance. Seventeen makes an appearance to reveal the trainees' third mission.

Round 3 shows the trainee teams as they make their through an interim check at a special venue, rehearsals and a final performance, set on a stage that is larger than they anticipated. The trainees are tasked with completing the 'Seventeen Legendary Mission', covering three songs which they must also self-choreograph. In contrast to other rounds, the 15 trainees learn that the number of &BALLS they receive will be announced live after each performance in the presence of the producers and other trainees.