Agatha Christie was a master of this - her best example is "The Murder of Roger Ackroyd." I imagine it felt obvious to her as she was writing it because she knew what she was doing - she could see all of the clues she was leaving. As a reader, when the twist was revealed, I couldn't believe I hadn't seen it. I reread the whole book again from that point of view to see what I hadn't seen before. Brilliant! So write your story anyway. Have a beta or two read it without spoiling the surprise and see if they picked up on the clues too quickly. If so, see if there are lines here or there that could be reworked to help disguise the twist better. But most importantly, just enjoy the pleasure that comes from the process of writing. We'll all be here to enjoy your creation.
