Summary from Goodreads:
In 1923, an amateur archaeologist brings Mary Russell and Sherlock Holmes an inlaid box from the Holy Land and then promptly dies in a suspicious traffic accident that leaves the master detective and Mary with an dangerous manuscript seemingly written by Mary Magdalene.
A very neat little mystery that promises a great deal in the way of theological intrigue and misogyny yet resolves itself in a mundane way. Much to Holmes's chagrin. How boring for him and a nice change for the reader.
I liked this installment of Mary Russell's "memoirs". It continues in Mary's theological vein, with the arrival of a purported letter from Mary Magdalene where she identifies herself as an apostle, but rather than the death-defying cat-and-mouse games of the first two books it has a bit of a slower pace. Also interesting to learn a bit about the Russell/Holmes marriage. One of the best scenes was one where Holmes attempts to out-logic his gut reaction to Mary working undercover as a misogynist's secretary; he views Mary as his partner in deduction, not a subservient wife, yet really has to fight an innate urge to keep his loved one from harm. A slightly-related scene that made me laugh was one where Holmes attempts to cajole Mary into something and she describes her nice warm bed as "invaded" by a cold, bristly male person smelling faintly of cheap gin and strongly of tobacco (I'm paraphrasing, since I don't have the book to hand but you get the picture); an excellent way to show intimacy between the characters without being graphic.
Dear FTC: I borrowed this from the library.