Murder At The Ice Ball - Lady Katherine Regency Mysteries, #3

When a tragic accident turns out to be murder, Lady Katherine finds herself embroiled in an investigation tainted by lies and deception. With conflicting witness testimony, mysterious neighbors who saw the impossible, and a secret someone would kill for, Katherine must dig into the dark side of polite London society to uncover the truth. Naturally, she has help. Maybe too much help. Along with her loyal maid, Harriet, her pilfering pug, Emma, and her Bow Street Runner friend Lyle, Katherine is joined by budding investigator Pru Burwick and her eccentric Scottish fiancé, Lord Annandale.
Katherine wouldn't mind their help so much if Annandale didn't keep bringing the insufferable Captain Wayland along. When the investigation takes a disturbing turn, Katherine gets a lead that indicates someone close to her may not be telling the truth, and she must make a tough decision. Protecting her loved one means keeping a secret from her closest allies. Hopefully it does not also mean letting a killer go free.