On the Lost Island level (if you missed it first time you can replay any chapter) there is a checkpoint called, 'The Hedge Maze' you will go into a maze to look for a crank to open a door. Your aim is to burn all the hedges in this area. I went down the stairs from the door you open and then round the edge in a clockwise pattern burning all the hedges. I went twice round as I missed a couple, there are a few in the middle that are a bit more tricky to see but you can see all of them doing it this way. Upon burning the last hedge the achievement will pop. If it doesn't, you missed one. The area is not that big but be sure to check the very edges as there are a lot by the walls. Good luck.