RHEM3: The Secret Library continues the story from its two predecessors Rhem and Rhem 2: The Cave. Your task is to once again help the brothers Kales and Zetais to discover a new part of their fascinating world. After you have found a letter from Zetais with instructions you start the journey to Rhem once again...

On your arrival you meet Kales who has discovered that a mysterious artefact, a black gem, is hidden somewhere on Rhem. Because the doorway must be opened by two persons but remains open just long enough for only one person to slip through, you are the only one accessing this new part of the island. Again, on your own you must uncover these new secrets of Rhem.

Rhem 3: The Secret Library sets you into a huge, fantastic world full of strange vehicles and buildings, unknown mechanisms and machines, secret passages and doorways. Adventuresomeness, logic, attentivness and the ability to solve engimas will help the player to slowly but surely unveil the mystery of this new adventure on Rhem.