Television experimenter Curtis Drew sets out to combine the X-ray with television to aid surgery. However, he discovers instead 'pure' television-invisible 'Z-rays' which have the potential to receive and record any situation-anywhere. Nothing is private any more. The secrets of the warlords, the immoralities of the masses, the hidden crimes all be lie exposed before the merciless, penetrating power of the invisible Z-ray. The invention could benefit humanity, yet to Drew it opens up more lucrative possibilities. He becomes a scientific 'Peeping Tom' and blackmailer, but when murder results, Scotland Yard becomes interested...
Maria Black, M.A., Principal of Roseway College for Young Ladies, is faced with murder in the cinema when a stranger seated in Number 11 on Row A is found to be dead. Assuming her role of detective, she becomes Black Maria - the crime solutionist. Working with Inspector Morgan, the local police chief, they go behind the scenes of a cinema, into the homes of those workers who'd maintained the entertainment industry- and into the recesses of a killer's mind.