Here is the complete plot summary for ep. 17:
“Hat Trick” – While searching for a missing Mary Margaret, Emma is kidnapped by a man whose affinity for hats has him teetering on the edge of madness. Meanwhile, viewers will be transported outside of the fairytale land that was for the first time when the Evil Queen persuades a skillful man of magic to come work for her one last time and travel to Wonderland in order to help steal something from the Queen of Hearts, on “Once Upon a Time,” SUNDAY, MARCH 25 (8:00-9:00 p.m., ET) on the ABC Television Network.
“Once Upon a Time” stars Ginnifer Goodwin as Snow White/Mary Margaret, Jennifer Morrison as Emma Swan, Robert Carlyle as Rumplestiltskin/Mr. Gold, Lana Parrilla as Evil Queen/Regina, Josh Dallas as Prince Charming/David, Eion Bailey as August, Jared Gilmore as Henry Mills and Raphael Sbarge as Jiminy Cricket/Archie Hopper.
Guest starring are Tony Perez as Valet, Giancarlo Esposito as Sidney/Magic Mirror, Jennifer Koenig as Queen of Hearts, Sebastian Stan as Jefferson, Ali Skovbye as Paige/Grace, Donald Adams as vendor, Roger Daltrey as Caterpillar (VO), Paul McGillion as Knave of Hearts, Laura Wilson as Mrs. Grace and Scott E. Miller as Mr. Grace. http://www.ksitetv.com/once-upon-a-time/once-upon-a-time-episode-17-hat-trick-spoilers/12367
Plus, we find out that the Queen of Hearts is played by an actress who is making her debut in OUAT: Jennifer Koenig. The two theories that either Regina or the nurse from the psyche ward are the Queen of Hearts are out.
It’ll be interesting to see what role Tony Perez as Valet plays. He is also Henry Mills (aka Regina’s father) in FTL. We also get to see him in episode 18.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy