Once Upon a Time returns this week to show Glinda’s role in the mission to stop Zelena. Check out the latest stills from ABC and read the full synopsis below!

The clock is ticking faster for Hook on this week’s Once Upon a Time season 3, episode 19, “A Curious Thing.” How long does the pirate have to drain Emma’s powers before Zelena turns her sights on someone close to the Savior? This week’s synopsis and promo show the first victim Zelena plans to take from Emma’s life, and he may be the most important.

In the stills from this week’s episode, a familiar book appears in Regina’s arms. The storybook has a strong history of providing useful clues, so perhaps the book can provide Henry with a similar experience and spark a bit of his memory before it is too late. Meanwhile, in the year that was, Glinda makes her debut!

‘A Curious Thing’ Synosis:

Zelena threatens to kill Henry if Hook – whose lips have been cursed by the Wicked Witch — doesn’t proceed with kissing Emma, which will drain all of her magical powers away, and things begin to heat up between Regina and Robin Hood. Meanwhile, back in the Fairy Tale Land that was during the past year, Snow and Charming go in search of Glinda, the Good Witch of the South, to see if she can help them defeat Zelena, and the curse that will ultimately send the Fairy Tale characters back to Storybrooke is cast — but from an unlikely source.

Henry’s triumphant return this week places him in an all too familiar scenario. Unfortunately, the son of the Savior’s false memories block his ability to recall that being held captive by characters from fairy tales is nothing out of the ordinary.

Watch Once Upon a Time season 3, episode 19, “A Curious Thing,” Sunday, April 27 at 8 p.m. ET on ABC.