I just finished a delightful English Country House mystery written by a Bulgarian author in English! The Hunt For Sonya Dufrette by R.T. Raichev contains more red herrings than the North Sea! It introduces a sixtyish librarian amateur sleuth who teams up with a retired member of the military club she works at. The plot kept twisting, changing, and re-forming as I read - just as you (and the librarian) had an "aha!" moment, something totally unexpected dropped in! "We" solved the mystery several times .... and then started again!
Highly recommended delightful read - and best of all - it's the first book of a series!