Imhotep!

So, it seems I missed a book in Simon R. Green's Ishmael Jones series, but given these are stand alones much like Agatha Christie, not a big deal.

Any rate, Death Shall Come involves Ishmael and Penny joining the Colonel (also known as Stuart) at his in-laws estate where George Cardavan is unveiling his latest acquisition, the mummy of Cleopatra the First. The entire family will be there, from George's mother and in dementia father, his trophy wife, his kids and their spouses. And his resident Egyptologist, Dr. Rose. 

The mummy, of course, comes with a curse.

So when George shows up dead in a locked room with a missing mummy, you can bet everyone is thinking Boris Karloff walks among them.

And indeed, there are more than a few bodies that show up along the way, but, as is common for this series, The curse of the mummy has nothing to do with a supernatural curse. But we do get a glimpse at who Ishmael may have been before he became Ishmael. Which is in and of itself interesting.

Good locked room mystery, with an unusual solution.