Post History
While I believe that you can't completely determine whether a story is too dark from the summary alone, I also have gotten a strong sense of what I think is most likely to be the case. I think you...
Answer
#3: Attribution notice added
Source: https://writers.stackexchange.com/a/41514 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
While I believe that you can't completely determine whether a story is too dark from the summary alone, I also have gotten a strong sense of what I think is most likely to be the case. **I think your story is not too dark, but it may be too graphic.** Based on the outline you provided, you are throwing the readers into a world of cruelty and torture from the very beginning. Unfortunately, at this point, the reader has not yet developed a bond with the characters and all this torture will not provoke their sympathetic emotions in the way you might expect. The reader hasn't had enough time to truly care about the characters yet. "Darkness" ties in strongly with emotion and the readers' reaction. You want your readers to connect with the character and feel, "Oh God, that's horrible! She doesn't deserve this." when they read the tragic parts, instead of "This is inhumane, but lots of people suffer this in real life. I don't really care about this character in particular." There is not enough emotional depth for it to be considered dark yet. Since I have to give a reference apparently, think about popular dystopian novels like Divergent or the Hunger Games. Both books start at a relatively peaceful, non-traumatic point in the main character's life, so the reader can get a feel for who they are and relate to them as they go through daily life and may have some relatable thoughts. Later, the horror of what happens provides a significant contrast and allows the reader to question the cruelty of the dystopian society, because they have a reference point. On the other hand, if you do nothing but subject the characters to torture, torture, and torture, it may escalate to the point where readers are turned off because it's getting too graphic. Don't hurt your characters excessively for the sake of hurting them. The reader will probably see right through that. So, while your story so far is not too dark, do your best to not make it too graphic.