Living in the luxurious Arcanum building - with its interior balconies perfect for playing tag, an elevator like an iron birdcage, and quirky neighbours behind every apartment door - has always been fun and games for twelve-year-old Minerva Keen . . . until her neighbours start getting poisoned. Anyone could be next, and everyone is a suspect, including Minerva herself.
To clear her name and help the police crack the case, Minerva starts her own detective club. So what if it only has two other members, one Minerva's accident-prone daredevil brother and the other the biggest and quietest kid in school, who happens to be afraid of his own shadow? Minerva knows that with her brainpower, the club's sleuthing skills, and case files full of suspects, they can unmask the poisoner . . . hopefully before it's too late.