A young adventurer-in-training keeps her wits about her and her eyes on the prize despite an uncooperative mother, snickering classmates and her own clumsiness—for there is Lost Treasure to be found, and more, in her seemingly ordinary Connecticut town. Modeling herself after the intrepid heroine of her absent dad’s adventure novels, Tiernay plunges headlong into an investigation after overhearing a restaurant conversation about lost Revolutionary War Era gold, and then learning that a sword of similar vintage has vanished from a local antiques shop. Some library research, a bit of spying and a late-night chase later, she and Kevin, nerdy but game son of the man her mom is dating, find themselves locked in an abandoned cellar with not only the sword, but an entire trove of stolen loot. Simner deftly tucks in clues, subplots and enough tongue-in-cheek humor to keep the suspense from turning scary. Her focused determination overriding all obstacles and mishaps, Tiernay makes an appealing protagonist, and by the triumphant close she’s not only helped solve a rash of local crimes, but has even unearthed that gold. Fine fare for recent Cam Jansen and Encyclopedia Brown graduates. (Fiction. 9-11)