This is the moment a thug threatened a shopkeeper with a 10-inch knife during a terrifying robbery - while wearing a SUPERMAN t-shirt. Derek Brett, 37, had stolen the blade from a homeless centre before drinking a bottle of brandy and raiding the convenience store. Dramatic CCTV footage shows the thug calmly walking towards the counter before pulling out the large kitchen knife. Brett - who is wearing a blue t-shirt with the Superman logo on - can be seen struggling with the brave shopkeeper.