A group of orphaned siblings convert their inherited lakeside house into a summer lodge and pursue a local rumor of buried treasure. As they open the hotel they piece together baffling clues—anonymous notes, bottled messages, and a torn map—and confront rival seekers and escalating threats that culminate in theft and danger. Through careful sleuthing, traps, and recovered fragments they expose a thief and unearth the forgotten hoard, while family ties strengthen and a romantic relationship develops between two of the siblings, concluding in a safely resolved, upbeat ending.