Nancy Drew... Trouble Shooter (1939) on Netflix

Plot summary

The Drews take a vacation at Sylvan Lake, but Carson Drew's real business there is the defense of Matt Brandon, whom Nancy calls Uncle Matt. Matt is accused of killing his neighbor, Henry Clark, after a long feud over a land border; Matt was overheard threatening Henry before Henry went missing, and no body has been found. The local sheriff, Barney Riggs, sees no reason to doubt the charge. Ted Nickerson, Nancy's boyfriend, is vacationing at the lake too, and Carson's instant attraction to Edna Gregory leaves Nancy fearing she will lose her father's attention. Nancy and Ted take up the search for the real killer.