Yes you can guess the murderer easily 
Very well before our protagonist yeah
But yes you can't guess the reason.. so +1 here 
And yes we have read this many times stories about serial killer and also about young girls targeted ..
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Interesting things in story
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Only thing that is interesting here is all the Greek Mythology refrences 
Yes they are not which people will know generally 
There are many new and deep refrences to the Greek Mythology 
And appreciation towards Tennyson 
Also we get to know about him more 
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The reasons to few of the methods of psychoanalysis was new and interesting and the conclusion.
(Which was also there in his first book)
Explanation to it was interesting and yeah kind off new too ..
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The conversation protagonist has with their own therapist is the interesting and how they found the mystery was interesting part 
(It happens first book too)

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And writing and as good like the first book 
And the pace too was good 
You can read it in a day ..
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Spoiler ahead 
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Please don't read the spoiler it's big one
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What's up with 
Dead cheating husband's   ??
Same thing in both his books 
And 
This thing with teacher having affair with students 
This thing I have seen a lot in many new thrillers 
Yes cheating husbands and boyfriends is also common factor in many thrillers ...
Tired of this ..really ..!
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She was thinking all along that Persephone and Demeter took her husband away 
But actually they saved her ...🙌