The Clue of the Broken Locket is the eleventh volume in the Nancy Drew Mystery Stories series.
The plot primarily deals with the adoption of 18-month-old twins, and the reuniting of two families. Carson Drew handles an adoption for the wealthy show-business couple, Johnny and Kitty Blair. The Blairs invite Nancy and friend Bess Marvin to a celebration, where the Blairs and other guests are distracted by heavy drinking and smoking. Nancy manages to secure some articles found with the abandoned babies, clothing and the mysterious broken half of a locket. Nancy tries to aid the incompetent maid in caring for the children. The maid is fired as a result and, with her boyfriend, plants stolen jewelry in Nancy's car as revenge. Nancy tries to help the Blairs' butler Rodney, and a nurse, Ruth Brown, who it turns out are long-separated twins themselves. Nancy must discover the whereabouts of the twins' missing natural parents, encountering resistance from the spendthrift, and nearly bankrupt Blairs.
Nancy, Bess and George find strange events happening when the visit Misty Lake. They meet Cecily Curtis, who seeks Nancy's help in solving two mysteries: one concerning Cecily's fiance, Niko Van Dyke, a popular singer who believe his record company is cheating him of royalty payments; the other, involving a family treasure hidden before the start of the Civil War. Cecily's only clue is half of a gold locket. Nancy's investigation leads to Pudding Stone Lodge and involves the sinister Driscoll family.
The cover art for the original dust jacket is uncredited. Russell H. Tandy drew the frontispiece and original three internal illustrations for the volume in 1934. A facsimile of this edition is available from Applewood Books. In 1950, the cover art was modernized by Bill Gillies. In 1962 the cover art was modernized again, by Rudy Nappi. Nappi inserted himself as an old man with a pipe on the cover. In 1965, when the story was revised, Nappi made another cover, in print today, showing a dark, sinister lake, with Nancy, Bess, and George discovering the title object while wading to a ruined boat.
- Beginning with this book, Mildred A. Wirt has returned to writing for the Nancy Drew Mystery Stories series and will continue to write for it until volume 30, The Clue of the Velvet Mask.