Both are by H.P. Lovecraft. 'The Shadow Over Innsmouth' is my all-time favorite of his works. He doesn't just stumble across them, it explains how the town they lived in was infamous for being weird. It's not as gory as you'd think, actually.<br/><br/>If you're looking for something incredibly creepy, I'd recommend 'House of Leaves' by Mark Z. Danielewski. A man finds a spatial anomaly in his house, gets lost in it. It's really trippy, though.<br/><br/>For more gory stuff, go with any of Junji Ito's manga.