In Love and Murder: An Oxford Murder Mystery (Bridget Hart, Book 4) [Audiobook]

Deception. Death. A deal with the devil.
When Dr. Nathan Frost, a lecturer in German literature at Oxford University, is invited to a lavish party at the country house of a wealthy businessman, he knows there'll be a price to pay. After all, as an expert on the legend of Faust and Mephistopheles, he can recognize a deal with the devil easily enough. But even he's not expecting such a sinister end to the evening.
Called to investigate a suspicious death at a country house, Detective Inspector Bridget Hart is surprised to find a government minister among the party guests. Her team must navigate powerful interests to find the truth. But in a world of favors, backhanders, and corruption, nothing is as it seems and nobody can be trusted.