Dangerous Days is Deary's new history series for adults, or at the very least young adults. It's in the juvenile section at my library, but that's really not an appropriate classification, at least not to me, as Deary discusses death in graphic medical detail and brings up sexual intrigue in, again, worrying detail. I'd save this for a preteen at the very earliest.
That said, I kind of love them. This is basically Deary's first series, Horrible Histories, that has been updated and aged up for an older audience. It has also been corrected for accuracy, as many of the Horrible Histories were written before several recent and major advances in historical research rendered many of them inaccurate. However, Deary sticks to his strengths here, concentrating on the little horrible details that really bring the past to life. Great books for the teenager who has aged past the Horrible Histories but still wants something fun and gruesome to read, or for the adult who refuses to age past the Horrible Histories but also wants something fun and gruesome to read. I'd definitely recommend these.