 A car carrying two Ministry officials, enroute to investigate the budget overruns on Professor Rushton s latest project, vanishes under escort. Steed goes to investigate, and discovers the hard way where the money has gone; to build a device capable of shrinking anything to a fraction of its normal size. While Rushton has great science- and industry-oriented plans for the device, his assistant Chivers has plans of his own... to make a profit, and dispose of anyone in his way. Steed, inches tall, manages to telephone Emma with a warning, but she is captured by a co-conspirator of Chivers, and next faces the shrinking machine. How will Steed and Emma get through this one?