As Trian flew down towards main street and his intended scare cum freakout at Granny's, he felt a "cold" sensation come over him. He knew instinctively that there was a hostile energy field in operation. Landing on a roof he generated the chameleon effect to blend in with the roof and studied the road below. Every time he looked at the road he felt odd, his eyes were aching as if he had a focusing problem. Indeed, it was reminicent of looking at a Hexenbeist at work. So that was it, there was something trying to hide in plain sight. He just had to concentrate and use The Second Sight.
A couple of minuets later and Trian finally found The Dark One. He was shocked. The Dark One, here already ! So what else had they overlooked?
Some careful spying and scrying soon revealed the truth. Ursula and Cruella had slipped into town the day before. Trian consulted with The Blue Fairy who realised that they must somehow have opened a way in for The Dark One. Trian also learned that the Fairies had been trapped until a week ago in The Sorcerer's Hat. So how had they got out? Henry finding out on the Internet! A likely story. Things were not right.
Some more scrying and "listening at keyholes" and Trian realised that The Dark One was setting up a trap for The Dynamic Duo, to resurrect Mom. Well that wasn't going to work, they had resurrected her with The Water of Lake Nostos / The Wishing Well and some blood over a year before when Henry was in Neverland. Which also meant that Mom and their sisters were not coming to Storybrook. Trian phoned Dad with the news. A hurried decision was then made to dupe all parties concerned. Rex, with his coercive abilities could have fun imitating Mom.