It's a freezing, foggy morning as the Searoad Mersey II docks at Melbourne Port. We've had a tip off that the truck we're looking for is on board. Hours later, it appears, loaded with Tasmanian logs. We chase it. Trees from Tasmania's public forests are not meant to leave the island. But two years after Victoria banned logging in its own state forests, Four Corners has discovered there are Victorian sawmills now relying heavily on Tasmania for supply.