Book of Secrets (W.I.T.C.H.)
The Book of Secrets was an artifact that featured in the cartoon series W.I.T.C.H.
The Book of Secrets was a large book that opened only to its owner who was Prince Phobos. It contained all his secrets and plans locked inside of it such as those that he had for Elyon. There were many attempts to open the book and learn its contents but all these failed until the Guardians used the Seal of Phobos to open it at which point they learnt of Phobos's plans to steal his sisters powers.