Secret is a synonym of Mysterious. Mysterious is derived from Mystery. Mystery is a synonym of Puzzle. 
Examine is related to Observe. Observe is a synonym of See. Favor is a type of See. 
Secret <--Synonym--> Mysterious --DerivedFrom--> Mystery <--Synonym--> Puzzle 
Examine <--RelatedTo--> Observe <--Synonym--> See <--IsA-- Favor 