A Clash of Spooks — Nic Saint

When Felicity Bell and Alice Whitehouse are sent to England on their first ever ghost hunting mission, they discover the woman who hired them brutally murdered with an ancient battle-ax. Now instead of figuring out how to rid Castle Windermere of its ghosts, they are drawn into the murder investigation instead. The plot thickens when a famous New York fashion designer arrives in search of her father, a CIA agent who went missing twenty-five years ago. Before he died, he was involved in the theft of a mysterious Russian device, now rumored to be hidden inside the ancient castle. With ghosts popping up all over the place, murderers and their victims running amok, talking rats making a nuisance of themselves down in the castle's crypt, Felicity and Alice soon have enough on their plate. So when Fee's fiance Rick Dawson is suddenly kidnapped and held for ransom, the two friends buckle down and show this particular haunted castle that nobody messes with Bell & Whitehouse once they get their groove on."