We start 6 months from the end of The Graduate. Elena has died in a car accident. Felicity, in her grief, pulls away from Ben, who cheats on Felicity. Meghan convinces Felicity to come back to NY for Noel and Zoe's wedding. After comments from both Noel and Felicity that they each have thought about what it would have been like if they were together (instead of Noel and Zoe), Felicity makes a wish and Meghan does a spell (with a book that was recently published) that sends Felicity back in time to the night Felicity and Noel slept together.
When Felicity realizes what has happened, she embraces the do over. Felicity breaks up with Ben as fast as she can and tells Noel she wants to be with him. The only person Felicity tells about the time travel is Meghan, and all characters - including Meghan - are confused by Felicity's manic and unusual behavior.
In the alternate timeline, Elena and Tracy fight about the Felicity/Noel/Ben situation and call off their wedding, and this time Meghan and Sean don't get married instead.