The Laughter of Dead Kings by Elizabeth Peters.
This is the sixth (and according to the jacket copy, the last) Vicky Bliss novel.
Life is back to "normal" for Vicky and John. They are visited at Vicky's home by an old friend from Egypt who informs them of the theft of a priceless antiquity, and begs their help in retrieving it. Of course, they agree.
If you've read any of the earlier Vicky Bliss novels, you will recognize the procedure. There's and extremely complicated plot with much gallivanting around the world and many encounters with old friends and nemeses, emphasizing the insular and cutthroat nature of the antiquities community.
Ms. Peters is an amazing writer, and I enjoyed reading this so much that I finished it in a single day. I do hope this isn't really the last Vicky Bliss book, but if it is, perhaps the author would consider another Jacqueline Kirby novel.