Season 13 of ABC's hit medical drama "Grey's Anatomy" will premiere in September and actor-director Debbie Allen on Monday took to Twitter to announce the title of the first episode of the season.

"Can't wait to share @GreysABC Season 13, episode 1 with you! Sit tight!" she tweeted along with a picture of the script titled "Undo." The episode is written by William Harper and Allen will be directing the episode.

As for the plot of the premiere episode, fans have been theorising that it will see Jackson and April deciding to call off their divorce. The duo welcomed a baby in the Season 12 finale and the newborn is expected to bring the duo back together. "I always, always, always hold out hope for Japril," actress Sarah Drew, who plays April, told TVGuide back in February. "I think there's always hope. Nobody's dead. There's always hope as long as they're both still breathing."

"Undo" could also see Meredith trying to terminate her relationship with Martin Henderson's Nathan after realising that her sister Maggie was interested in the new doctor. Meredith wouldn't intentionally hurt her sister, but Maggie will be devastated when she gets to know that Meredith hooked up with Nathan before Amelia and Owen's wedding.

As for the newly married couple, they will have to work on staying married."The rapidity with which they got married is going to be a piece of their story," Caterina Scorsone told Entertainment Weekly. "It took that level of spontaneity to get them down the aisle. If they had waited any longer, the nerves would have won. But now they have to figure out how to be married. That's a big question for anybody, let alone two people who are deeply wounded. A lot of their story this year will be negotiating this whole different dynamic, sharing a life and being vulnerable when you're terrified of all of that stuff."

"Grey's Anatomy" will return to ABC on Sept. 22.