PAWSitively Sinister (A Klepto Cat Mystery Book 11)

The Ivey family travel to San Francisco to help Arthur and his long-time friend, Suzette, clean out the mansion. News of the massive estate sale lures a variety of people, including former residents and long-ago visitors, each carrying stories of bizarre activities occurring there in the past.
When the klepto cat, Rags and his pawtner Koko make some ghastly and ghostly discoveries, everyone goes into research mode and they’re stunned by what they uncover - evidence of people gone missing, a treasure-trove of loot, and spirits unable to rest. This is by far the most PAWSitively Sinister story in the series.