What is another word for secrets mysteries?

Here are some words you could use instead of "secrets mysteries":

More formal:

* Enigmas

* Puzzles

* Mysteries (this is a bit redundant but can be used for emphasis)

* Conundrums

* Riddle

* Cipher

* Arcane knowledge

* Hidden truths

* Unsolved cases

More informal:

* Secrets

* Hidden agendas

* Unsolved puzzles

* The unknown

* The truth (used in a mysterious way)

* The big question

The best word to use will depend on the context and the specific meaning you want to convey.