The Longest Journey
Unlock the Book of Secrets in chapter 4
In chapter 1, a leaf (listed as organic plastic in the inventory) can be taken from the plant outside of April's bedroom in the Border House. This can be used on the flowerbed outside of Abnaxus' house in chapter 4. A purple flower will grow from the flowerbed, and the Book of Secrets (which is normally opened by completing the entire game) will be unlocked.
Contributed By: THayes.