Spoiler: 3/19/17 episode GOLD TAKES ACTION TO PROTECT GIDEON FROM THE TAINT OF DARK MAGIC, AND EMMA LEARNS THAT HOOK IS HIDING SOMETHING FROM HER, WHILE ROBIN AND ZELENA FORM A DANGEROUS ALLIANCE, ON ABC'S "ONCE UPON A TIME" Sean Maguire Guest Stars as Robin of Locksley and Giles Matthey Returns as Gideon "Ill-Boding Patterns" – When Gideon resumes his mission to kill Emma and become the Savior, Mr. Gold steps in to ensure that the use of dark magic does not poison his son. Meanwhile, Robin proves willing to ally himself with anyone offering the possibility of escape from Regina and Storybrooke. Hook gathers the courage to come clean to Emma, but not before she discovers he's been keeping a secret. And in a flashback to Fairy Tale Land, the legendary folk hero Beowulf sets his sights on Rumplestiltskin after the Dark One uses his powers to defeat the ogres and win the war for humanity, on "Once Upon a Time," SUNDAY, MARCH 19 (8:00–9:00 p.m. EDT), on The ABC Television Network. "Once Upon a Time" stars Ginnifer Goodwin as Snow White/Mary Margaret, Jennifer Morrison as Emma Swan, Lana Parrilla as the Evil Queen/Regina, Josh Dallas as Prince Charming/David, Emilie de Ravin as Belle, Colin O'Donoghue as Hook, Jared S. Gilmore as Henry Mills, Rebecca Mader as the Wicked Witch/Zelena, and Robert Carlyle as Rumplestiltskin/Mr. Gold. Guest starring are Sean Maguire as Robin of Locksley, Keegan Connor Tracy as the Blue Fairy/Mother Superior, Raphael Sbarge as Jiminy Cricket/Dr. Archie Hopper, Giles Matthey as Gideon, Brandon Spink as Baelfire, Torstein Bjørklund as Beowulf, Samuel Patrick Chu as Frightened Soldier, Chris Loubardeas as Reveling Soldier, and Angela Moore as Villager. "Ill-Boding Patterns" was written by Andrew Chambliss & Dana Horgan and directed by Ron Underwood.