Talk is cheap! It's action that counts! 
Detective Comics #351 is an issue of the series Detective Comics (Volume 1) with a cover date of May, 1966. It was published on March 29, 1966.
Synopsis for Batman: "The Cluemaster's Topsy-Turvy Crimes!"
Batman and Robin have to protect their secret identities on two fronts when Aunt Harriet and the criminal Cluemaster attempt to discover them. While foiling all of Aunt Harriet's attempts to learn the truth after finding the secret passage to the Batcave, they double stop Cluemaster's attempts to trace the Batmobile back to the Batcave.
After an extensive investigation, Batman and Robin manage to foil the Cluemaster, and as Bruce Wayne and Dick Grayson, they doctor film that Harriet made of them entering the Batcave to convince her that Batman, Robin, Bruce Wayne, and Dick Grayson are different people.
Appearing in Batman: "The Cluemaster's Topsy-Turvy Crimes!"
Featured Characters:
Supporting Characters:
Antagonists:
- Cluemaster (First appearance)
Locations:
Items:
Vehicles:
Synopsis for Elongated Man: "The Case of the Costumed-Made Crook!"
The Elongated Man plans to donate his old costume to Central City's Flash Museum only to discover it has been stolen. Ralph returns to Coast City to track down the missing uniform, which he traces back to hotel bellhop Billy Brown. Brown stole the uniform hoping that it would give him stretching powers. When he found that it didn't work, he began using the costume for crime. Ralph tracks down Brown and uses the costume itself to capture him. Elongated Man then delivers the costume to the museum for display.
Appearing in Elongated Man: "The Case of the Costumed-Made Crook!"
Featured Characters:
Supporting Characters:
Antagonists:
- Billy Brown (The Disappearing Crook) (Single appearance)
Other Characters:
- Various unnamed citizens of Coast City
- Flash (Cameo)
- Dexter Myles
Locations:
Items:
- Elongated Man's old uniform
Vehicles:
- Police Helicopter
Notes
- "The Cluemaster's Topsy-Turvy Crimes" is reprinted in Batman Family #2, Showcase Presents: Batman Vol 2, and Tales of the Batman: Carmine Infantino.
- "The Case of the Costumed-Made Crook!" is reprinted in Showcase Presents: Elongated Man Vol. 1.