Simple and quick, there was this Guy who got sent to a faraway house with his “adopted” sister iirc. The guy is a known detective that has special abilities of foresight, where he can see in the future, When he was with his sister in the house, he saw multiple futures where they were fucking. The sister is mostly naive, though I do think she is pretending. And by the last page, it was actually all seen by the detective further back in the past where he wants that future to happen.