As he passed over Arendelle, Jack picked up a cold, strange sensation, and knew it had nothing to do with his powers. He gathered the Big Four to share his discovery. Rapunzel and Merida perk up at the mention of Arendelle, because they were both invited to the coronation of the soon-to-be Queen Elsa. While the girls would waltz right into the castle, the guys would have to sneak in. “Won’t be a problem for me, of course,” Jack tries to joke, but the rest of the Big Four knew better than to bring up the fact that he was still invisible to many.
Finally at the Coronation, Hiccup tries to keep Toothless in the shadows and at bay. Jack walks around, searching for any sign of trouble. Merida struggles with the dress Queen Elinor had her wear, but tries to talk to as many people as possible (including Princess Anna herself); and Rapunzel, forgetting a little about the task at hand, dances the night away.
Jack grew impatient, wondering where that cold feeling had gone. It was odd that he ever felt it at all, as the cold never bothered him anyway. Suddenly from across the room, someone yells, “I said enough!” and that cold feeling wells up in his chest as Queen Elsa’s ice powers are revealed. Jack was left speechless, not because her powers were similar to his, but because out of all the people she could’ve looked at, out of everyone in the room, her eyes had landed on him.
"I’m telling you, she looked right at me!" Jack insisted, throwing his hands up in exasperation. "She saw me. She knew I was there. She … she believed in me."
EDIT: And for those of you who haven’t heard yet, yes, series 4 will indeed only air in 2016. They’re shooting a one-off special in early 2015 to air later that year. Series 4 will be shot in late 2015 or maybe even 2016 to air in… who knows?