Is it against the law to read (only) sexually explicit stories involving rape and torture of women?

Read only? no. But be wary of images. Is it really worth the risk? Find a safer hobby.

Reading in and of itself is never illegal. Viewing certain photogs/images certainly can be. You're on dangerous ground either way and your interest in this material could attract unwanted attention in the form of a search warrant for your computer where you might have images and/or movies of child porn. Find a different fantasy.

You have the freedom to read what you want. You would not have the freedom to posses these books if they contain actual photographs of underage girls. If you download this stuff from the Internet you increase the danger that Homeland Security may decide, rightly or wrongly, to look into your prurient interests.

The short answer is no. Only reading stories doesn't violate the law. Most federal and state statutes on this subject relate to possessing or distributing images of underage children, not descriptions of them.

More information is needed to really answer this question. Your question may involve child pornography, so if in doubt, do not.