The Mystery of the Missing Necklace is an installment in the Five Find-Outers and Dog series. The plot revolves around the theft of a valuable necklace from a wealthy local family. The Find-Outers take on the case, tracking down clues, interviewing witnesses, and trying to outsmart the thief, often having to contend with their nemesis, Mr. Goon. The mystery is a classic whodunit, focusing on the children's ability to notice details missed by the police.