If you read When She Woke by Hillary Jordan you can skip this one. The concept is similar: offenders (sinners, in this book) are identified by colors. Thus, blue for lust, yellow for greed, black for sloth, red for wrath, green for envy, and purple for pride.
And what is Lexi's sin? Since she has extremely beautiful Turquoise eyes... you can guess.
So she is taken prisoner for her "sin" and sent to live with other sinners that, really, you would think that since they aren't real "sinners" they would act like normal people. But nope, they act like savages that haven't seen a woman before...
Anyways, this is another dystopian crap that made me waste more money.