. ♪ so i'll tell you ♪ when i see you again ♪ when i see you again >> that is charlie puth singing.f the most successful musical collaborations of all time. "see you again." >> and, as abc learns, he saw the final piece of the film of franchise's puzzle. ♪ >> reporter: see you again, performed with wiz khalifa, honoring the late paul walk ir. the song broke records, for nearly a month and scoring three he composed the melody during a meeting. he says it took only a matter of minutes. >> my friend had passed away in 2012. i'll never forget, the moment i found out he was no longer living, i texted his phone. i was like, see you soon. how about see you again. ♪ it's been a long day without you my friend ♪ ♪ and i'll tell you all about it when i see you again ♪ i think i had in a matter of 30 minutes about 100 people walk in the room, executives walk into the room, who is this kid? nobody's able to nail it and he did it in ten minutes. i'm supposed to be like oh, i had no idea. i my it was going to change my life. >> reporter: he looked the part of a pop star. but it's clear there is a