Midston is chosen as the site for an important Science and Industry Fair, and Danny thinks up the idea for the University's display - an automatic house!

Before the Fair, Danny, Irene and Joe use their special passes to visit the house alone and examine the gadgets: the alarm clock that flips a person out of bed and brings him his clothes; miniature robots that scuttle across the floor picking up litter; the umbrella rack that hands out umbrellas by itself!

Suddenly Joe trips and falls, breaking the mechanism that opens the doors to the house. Danny and his friends find out that the windows cannot be opened or broken. They are trapped inside with no food or telephone - and the Fair does not open for three days!