Grey's Anatomy season 12
April goes into unexpected labour during Amelia and Owen's wedding ABC

It's an emotional day for almost all the characters in Grey's Anatomy season 12. Amelia and Owen are getting married, Arizona and Callie are still dealing with the aftermath of their custody battle for Sofia and April and Jackson will have a huge moment in episode 24 called Family Affair.

Click here to watch the episode via live stream on ABC Go, or click here to watch it online on the ABC website (only in the US).

But the biggest shock of the finale episode of the 12th season of ABC's long-running medical drama is the return of Cristina Yang, Owen Hunt's ex-wife.

"She still feels like she's Owen's guardian. And she takes that role very seriously. She still has that allegiance to Cristina, so she has some issues with [the marriage], Kevin McKidd, who plays Owen, told TV Line. "And she also has her own issues with Amelia. so there's some friction between them."

A sneak peek released by ABC reveals that Amelia will have a meltdown just before her big moment and will close herself in the bathroom.

Meredith and Maggie try to convince her through the bathroom door but that doesn't go well. Hence, April brings Owen who reassures her as she stays disheartened about someone's absence during her nuptials. "It doesn't matter. If they don't want to be here, then they shouldn't be. We don't want them. They don't get it, and they don't have to. I do, and I'll be there. And the only one I want there is you," he says to his would-be wife.

Later in the episode, April goes into unexpected labour while at Meredith's house and luckily Dr Ben saves her day. He offers his help to safely shift her to the hospital but the ongoing rain prompts April to take the decision of delivering the baby at home.

The official synopsis of the finale reads:

"Meredith and Maggie support Amelia on an important day; Jo reveals that she has been keeping secrets from Alex while Arizona and Callie deal with the impact of their custody arrangement. Meanwhile, Ben leaps into action to help a friend."

It will be interesting to see how the romantic equation will change between Jackson and April after she delivers her baby.

Grey's Anatomy season 12 episode 24 will air on 19 May at 8/7pm CT on ABC network.