Periscope Peril

Princess Purl has lost her tiara and it turns out it's been taken by two naughty castle trolls who parade around showing it off high up in the castle. Bevel pole vaults over the wall to get it back, but he looks straight into the trolls' special goggles and is frozen into a statue. Then Purl rushes in and is frozen as well, and so is Bob. It's down to Bitz to work out a way to unfreeze everyone and get the tiara back without the trolls seeing her and turning her into a statue too.