Thoughts on, and a place to discuss, the plot details we can't reveal in our review.
Leaving aside for the moment the larger issue of whether hypnosis can erase someone’s memory of the most important thing in his life, implant criminal suggestions that subconsciously control his actions, and seemingly entirely change his personality, the biggest plot hole in Trance seems to be that the painting thieves really do come across Dawson entirely by accident. Yes, Cassel lets McAvoy pick the hypnotist that will mess with his brain, and McAvoy chooses Dawson based on his vague, suppressed memories of her. But as near as I can tell, Cassel comes up with the hypnotist idea entirely on his own—which makes his plan neatly merge with Dawson’s original plan, just as her plan is in ruins because the painting and McAvoy’s memories of it are lost. That’s a mighty large coincidence that requires a mighty small world (or possibly just a more universal faith in hypnosis) to work. Wouldn’t the pieces have fallen together better if McAvoy had suggested the hypnotist, again out of submerged memories? Subconsciously, he knows she caused the problem in his head, and he knows she can fix it. If he were the one to suggest seeking her out, and to get the plan back on track, the whole thing would be a closed loop. Instead, it’s two broken semi-circles bluntly forced together by contrivance, unless there’s something I’m missing about the storyline.