L/S of the interior of an electricity plant.
Various shots of pieces of machinery in the plant - all weird shapes. Giant insulators are prepared for "terrific tests." The men who are going about their work look tiny compared to the massive machinery. Top shots of the strange shaped insulators. M/S of a man working in a control room - lots of levers and gauges. A large group of people are gathered at the back of the plant to watch the experiment.
We then see "Leashed lightning - giant sparks up to 20 feet in length - death to anyone in their way." Squiggly light is seen jumping between insulators in the dark.
Was an item in Pathe Pictorial issue number 641.