Simon has to fire the canon to open the port cullis and get the crystal. Everything is inside a cage about 1 metre high, so he has to move around on a car mechanics trolley.
He has to deduce that the canon and candle are on separate pulleys, crank them both, then go and get the crystal from the port cullis....phew! ...and all in three minutes..
(once you can see the picture below, move your mouse over it o play the video)
when you've finished, just close this window!