I'm torn between fully supporting this, and supporting it with one suggestion. "Promise and Peril" has a very good emotional/narrative "oomph" to it, and may retain attention more than alternatives. However, Desrtopa makes a very good point about the target demographics, and I think something less qualifiable as "dramatic" than the word "Peril" might be preferable. Small things, but bigger names, bigger publishers and bigger money have seen books make it or break it by their name.¹ (1. Personal conjecture and extrapolation - no formal study has been made or read to establish this belief. All I know is that publishers spend big money and lots of time on having the right title, from someone in the industry, and there's probably a reason for that, it having an effect on success of publication seeming the more plausible one.)