Tom Hardy, ex-Spitfire ace and Dave Rogers, Radar operator, were a night-fighter team. They flew in a Beaufighter, but they never got results. Sometimes the radar broke down, once it caught fire. They even found themselves chasing friendly planes.
Then something new was added to the team. On their night flights it was always with them, an unearthly presence glowing with an eerie green light, like a being from another world -- and it turned Tom and Dave into real night-fighter aces.