Emma Hook wedding
Emma and Hook in Once Upon A Time season 6 ABC

This Sunday's (7 May) episode of Once Upon A Time season 6 will feature Emma Swan and Killian 'Captain Hook' Jones fairy tale wedding, and the looming threat of Black Fairy will apparently not dampen the couple's big day.

Episode 20 is titled, The Song in Your Heart, and the official synopsis reads as follows:

Actors Jennifer Morrison and Colin O'Donoghue, who play Emma and Hook previewed the big wedding episode. O'Donoghue told TV Line, "At this point in time, they've just decided whatever's going to happen is going to happen. We need to make the most of time that we have together now because it's Storybrooke and you never know what's going to happen."

"There's a little glimmer of hope in the middle of a pretty desperate situation," he added. Co-star Morrison too echoed similar sentiments and told the outlet, "And we know that we want to be together. We know there are no doubts about that. We just want to move ahead with it and enjoy the moment."

In flashback

Snow and Charming make a special wish that Emma will be protected. The result of their wish has the whole kingdom bursting into song which infuriates the Evil Queen. Meanwhile in Storybrooke, the Black Fairy announces her plans to unleash another curse on the town while Emma and Hook prepare for their wedding.

This Sunday's musical episode will feature a solo song by Morrison titled Emma's Theme. The House actress said, "A lot of the song that we shot yesterday (Morrison's solo, titled "Emma's Theme") is about Emma getting to that place in her life, which I think kind of marks the final transformation from ugly duckling to swan. She overcomes the last of her fears and baggage and realizes that this song has been within her, her whole life, and it holds a power that she didn't realize."

O'Donoghue too previewed happy moment in the episode. "In [the group number] or the previous scene that we filmed, it's all happiness. There's no negative aspect. They know that what's going to happen is going to happen, and they don't care. They're just expressing how much they love each other, and..." he said.