The picturesque seaside city of Calendula (pronounced Ka-len-doo-la) occupies the southern curl of Camino Bay, in California's rugged central coast. The Widow O'Keefe, Calendula's reclusive patron of the arts, has passed away. For one day only, her mansion is being opened to the public, before everything in it-including her famous art collection-is auctioned off. Three men acting suspiciously at the mansion catch the attention of the Mysterious Adventures Society kids. Are they summer tourists wandering unpredictably around town? Are they buyers here for the auction? Or are they up to something sinister?With the pressure mounting and their warnings ignored by adults, the kids realize that to stop the central coast's crime of the century, they'll have to stop it themselves.Calendula Proof is a story about friendship proving stronger than fear, and believing in yourself, even when no one else does.