Whilst on their way back from a picnic the Plastic Team get lost and their car suffers a flat tyre.
Plas sees an old house in the distance and he, Penny and Hula Hula head towards it for help.
Inside Doctor Ventor is in need of help, as he is being robbed by a Gargoyle. The Gargoyle is trying to steal the Doctor's invisible ray.
Plastic Man and the Gargoyle battle and the Gargoyle is defeated, before Plastic Man can bring the villain to justice Hula Hula has an accident and drops the invisible ray, turning Plastic Man invisible and causing the Gargoyle to escape.
Doctor Ventor uses the invisible ray to turn Plastic Man back to normal, making him visible again; Doctor Ventor's assistants Mrs Green & Doctor Walker arrive from up stairs to see what the noise was about, whilst Doctor Ventor hides the invisible ray in his safe.
The Plastic Team start to search the house for the Gargoyle as they do a secret passage opens and kidnaps Penny.
Plas and Hula Hula go after her and fall into a trap as the Gargoyle sprays Plastic Man with an anti-plastic formula that freezes him.
Gargoyle seals the room and fills it with water and alligators. Hula Hula and Penny throw rocks into the alligator's mouths and they sink, whilst the water washes off the formula on Plastic Man and he can move again and the team escape.
Meanwhile Gargoyle breaks open the safe and steals the invisible ray, the Plastic Team chase him through a grave yard.
Gargoyle turns himself invisible to try and escape, he then kidnaps Penny again.
Gargoyle disposes of Penny and tries to lose Plastic Man in a underground tomb.
In the tomb Plas uses dust to make the Gargoyle visible again, Plastic Man then captures the Gargoyle and unmasks him.
The Gargoyle is really Doctor Walker, the assistant of Doctor Ventor.