Murder at the Altar is the first in Veronica Heley's Ellie Quicke series. It's free right now at Kindle US and UK. Originally published by HarperCollins, now by Joffe.
Kindle US:
https://www.amazon.com/dp/B0CJ314XWK
Kindle UK:
https://www.amazon.co.uk/dp/B0CJ314XWK