Nancy Drew: Mystery of the Glowing Eye
This is the 51st book in the series, dated 1974.
The main characters are Nancy, her friends Bess and George (both female), Ned, a friend of hers, and Marty King, an assistant to Nancy's father.
Nancy's concerned that Marty will try to take a certain case away from her. Meanwhile, Ned has been kidnapped, so that's one problem. Another is when a helicopter lands on their front lawn. There's also a mysterious note, 'Beware of the Cyclops.'
There's a glowing red eye at a certain museum, and the woman working there as receptionist is definitely not friendly. There's also a burglary on the campus of a school, a clothes chute people end up in, a plan to bomb Nancy's home, and a strange light that can hypnotize people for a while.
It's obvious who the main criminal is from very early on. It becomes a matter of trying to find the information needed to stop him, and trying to find where he has taken Ned. Several places are checked, but the crook keeps one step ahead of Nancy.
Not really so much a mystery, since the crook is known, but a story of trying to find a way to stop him and free Ned.
One very interesting thing is the effect of the culture. The particular version I read was done in 1974. There are several situations that Nancy and the others are in that a cell phone would have been of major value but there weren't any cell phones available then. This means they had to find an alternate way to communicate with the police and a ham radio is what they use.
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