Exterior. M/S of two men walking in a field carrying various items. They walk towards a cage made out of mosquito netting and put their things down on the grass. M/S of the first man climbing into the net cage, the other man passes in a bag and a tray. M/S of the first man inside the cage and the one outside passing the things in. The narrator says this is Rothamsted Experimental Station where they are conducting research into the Wheat Bulb Fly (Leptohylemyia Coarctata). The other man climbs through the net into the cage. M/S of the first man who has a tube in his mouth this is attached to a little test tube with a spout on the end, he brushes his hand against the wheat and holds the tube in the air, he then repeats the action. C/U of him sucking up a fly from the wheat through the spout. C/U of his face with the tube in his mouth, C/U of another fly being sucked off the net. Various shots of him sucking up flies. C/U of his hand holding the tube. The second man climbs out of the cage with a tray, he picks up the tray and a net and walks off.
Interior. M/S of the first man entering a room with a box of test tubes, the narrator tells us this is the laboratory where the flies are anaesthetised in a refrigerator before being handled. M/S of the man opening the lid of a refrigerator and putting the test tubes into it. C/U of his hand taking the test tubes out of the box and putting them in the fridge. M/S as he sits down at a desk, there are various jars and tubes on the table and seven small bottles containing different coloured paint, there is also a microscope there. He looks at the bottles and checks in a book. He picks up a green one and unscrews the top, C/U of his face as he does this. C/U of the jars and his hands unscrewing the top. He takes some clear liquid in a pipette and puts it in a very small dish. M/S as he takes the lid off a jar and puts it on the table. He gets up to open the fridge and takes out three test tubes. He sits down at the table with them and empties one into a glass dish. Various shots of him applying paint to the fly. M/S as he puts a fly in a jar with net over the top, he fastens it with a rubber band. C/U of flies in the jar. M/S of the second man releasing the flies into the cage. C/U of the jar on the ground.