Cleopatra's Dagger is a non-series title by Carole Lawrence, which, per
SYKM, is one of multiple pen names for Carole Buggé. (She's better known, I think, for her Ian Hamilton/Edinburgh series.) I haven't read any of her books, but
Dagger ticks off a couple of my favorite themes - historical mysteries and Egyptian history - and it has dropped to £0.99 at Kindle UK, as part of today's Daily Deal. So I'll probably give it a try. Since it's Thomas & Mercer, it's also KU, so if you have a KU subscription in either the US (where it's not on sale, at least right now) or the UK, you can also read it for free.
Kindle UK:
https://www.amazon.co.uk/dp/B099RVZMNP
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B099RVZMNP
A journalist in nineteenth-century New York matches wits with a serial killer in a gripping thriller by the prizewinning author of the Ian Hamilton Mysteries.