This is Book 4 in Ann Parker's "Silver Rush" series. The book opens with Inez Stannert, owner and proprietress of the Silver Queen Saloon in Leadville, CO, boarding a stage. she is headed to Manitou for a reunion with her sister and her now-toddler son. The journey does not go smoothly: a wealthy businessman dies in Inez's lap.
And that's just the beginning. Manitou boasts several mineral springs and touts utself as the "Sarasota of the West." A time before antibiotics and at the beginning of understanding how disease was transmitted, people ill with tuberculosis were easy prey for charlatans guaranteeing "the cure." Competition for patients and investors is fierce, and Inez finds herself in the middle of it all.
Her personal life is equally tumultuous, with Inez needing ti wun the affections of her son, deal with her Aunt Agnes, and sort out her domestic life.
But then, if Inez's life were easy, there wouldn't be much of a story, would there?
One note: I initially thought the Mercury referred to in the title was the element, used in refining gold and silver ore. It wasn't until the end of the book that I realized what Mercury referred to. Not Ms. Parker's fault: she left plenty of clues!
So now I wait for Book 5. I'm addicted.