Doctor Who: The Turn of the Screw

Charlie Sato has been chasing a bit of alien junk from England to Puerto Rico. He's finally got his hands on it - but now he's got to get it safely off the island. The aliens he stole it from want it back, and someone else has hired a group of thugs to get hold of it. And then there's the original owner - he might come looking too. All this for a screwdriver? Someone, somewhere must want to unscrew some pretty important screws.