Isaac is his son in the present. Isaac goes through his dad’s notebooks and learns about the chord. He goes back and finds his dad with Sylvie. He urges George to come back, but George doesn’t want to go back. He has chosen to trade that timeline as it was for a chance at a life with Sylvie.
Then we discover that the reason Sylvie and George had ended in the original timeline is because Professor Rex (George’s old lab partner who did not want Sylvie and George’s relationship interfering with their work) had shown up at her door one night after George left. But now because the timeline had been changed, Professor Rex ends up abducting Isaac to learn the secret means of time travel.
The story ends with Isaac “stranded in time” by Professor Rex who has sent him into the distant future. And Sylvie saying that we need to find Professor Rex.
Listen to it. I'd love to hear what you think.