Green Arrow, Flash and Dick went to Gotham City. They were on a rooftop.
Green Arrow: what are we doing here?
Dick: wait for it.
They saw a teenager in a red and yellow suit swing by on a grappling hook.
Flash: who is that?
Dick: Me. There I'm fifteen. I started when I was nine. They called me Robin. In my time the man who taught me everything about being a hero is dead because of The Dark One and countless others will die if we don't destroy the darkness in Emma.
Flash: ok what do we do?
They went back to Star Labs.
Harry: we can't use the speed cannon.
Barry: why not?
Harry: when Mister Grayson came through in a time portal it short circuited the main frame of the cannon.
Barry: but what if I run in the pipeline? If I go fast enough I could create a portal to Storybrooke like I did the first time I went.
Harry: that would work.
Barry suited up. He went down to the pipeline.
Harry: you ready?
The Flash put his thumb up.
Oliver: ok.
Dick: wait I want to say it. Run Barry….Run.
The Flash sped around the pipeline. Eventually he made a portal and ran through it leading him into StoryBrooke. He ended up in Granny's. he saw everyone clutched around an on conscious Emma.
Mary-Margaret: Barry!
Barry: oh no I'm too late.