The Murray twins step into the spotlight for the very first time in this book. Intriguingly, it seems to be set somewhere between the second and third books of the series. Meg isn't married yet, and Sandy and Dennys are supposed to be in high school during this installment. After accidentally disrupting an experiment, the boys find themselves hurled back to a version of the days before the global flood. In a strange oasis, they encounter Noah and his family, just before the construction of the famous ark, as well as some of the more corrupt and deeply unpleasant inhabitants of the ancient world.
Among the first four books I've read in this series, this one ranks last on my list of favorites. Similar to "A Swiftly Tilting Planet", this story involves time travel and either altering or maintaining the balance of the past. However, unlike the third book, our young heroes actually end up living in and having to cope with this historical time period where they've seemingly become trapped. It's not so much the premise that didn't sit well with this reader as it was the slow pacing combined with the author's particular high-fantasy interpretation of the biblically referenced time period. While the third book dealt with a completely fabricated timeline and family history, in this one, the author is directly drawing from a known source and twisting elements to suit her own purpose.
For some reason, L’Engle chose to depict ancient humanity as loincloth-wearing, desert-dwelling people who were extremely small in stature. By the end, I gathered that this was meant to imply that cross-breeding with fallen angels led to the more modern increase in height. (However, this doesn't explain the miniaturized size or nature of the water-detecting desert mammoths, which were described as being the size of dogs. There are also manticores, griffons, and "Virtual Unicorns" that only exist when you choose to believe in them... for reasons. >.>) Humanity's extremely long lifespan was also suggested as the cause for not reaching technical adulthood until around the centennial mark. As a result, Noah's 100-year-old daughter Yalith, who becomes the love interest for both brothers, is portrayed as a painfully naive teenage-minded girl. Talk about a serious case of arrested development!
To me, the twins didn't have distinct enough personalities. While they do prove to be more intelligent than they previously let on, they are still the most "normal" (i.e. vanilla dull) of all the Murray family. I found myself reading more to learn the plot rather than out of concern for what might happen to either of them.
Sandy and Denny's hazy knowledge of the Old Testament means they eventually do figure out the significance of the Noah they've encountered. But their lack of study and/or interest means they are incredibly slow to pick up on the fallen angels and Nephilim. (Apparently, in L’Engle’s highly mythological vision of the quickly summarized record, humans don't understand what the "winged giants" they've been breeding with actually are.)
Content Note: Contextual nudity (and its effect on the modern boys) is addressed with tact and cultural frankness. But this is the first book in the series to repeatedly reference awakening sexuality, which may come as a surprise to some readers. Lust and seduction are repeatedly depicted as they are used against the twins in an attempt to obtain information. However, compared to some of the more recent trends in Middle Grade and YA, the situations are relatively tame in terms of graphicness and end result.