Thanks to the spectacular success of the case of the sighing spiral staircase, Lockwood & Co. is now one of the trendiest ghost agencies in London. However, the metropolis is already shaken by a series of new shocking events: magical artifacts are being stolen, and their guardians are being brutally murdered. When an iron coffin is also recovered from a cemetery, its gruesome contents missing, panic spreads among the population. It's a clear case for Lockwood & Co.! But the team of Lockwood, Lucy, and George must put all their ingenuity to the test...