Surefire adventure, set in England in the reign of Charles II, around 1551, when the parliamentary army under Cromwell fought the royalists. Against this background, is woven the story of the search of emeralds for the King. ""Tosty"" Farringdon, , is sent to the home of his twin half-brothers, soldiers under Cromwell, to find the Yanburgh treasure, buried by their great-great grandfather in underground caverns. Toty alone knows the contents of the old parchment which divulges the secret, and his half-brothers imprison him when they learn of his mission. There are terrifying adventures in the dark underground, narrow escapes, and finally Tosty wins out -- finds the emeralds -- and saves the lives of the twins. A well-written yarn, warm personal relationships are well-drawn, there's a good bit of humor -- and the reader is spared the ""period-piece manner"" which slows up so many historical adventure tales.