Chris Bentley, author of "The Complete Book of Thunderbirds", describes the episode as "surprisingly effective" despite International Rescue's absence from most of its first half. He regards the scenes featuring the radioactive cloud as some of the "eeriest" of the series. Marcus Hearn, author of "Thunderbirds: The Vault", considers the "sinister" music accompanying these scenes to be the episode's most effective element; however, he believes that the appearance of Penelope and Parker "clutters" the plot. He also argues that Penelope's phobia "diminishes" her character just as the Hood's ill-conceived plans lead the viewer to suspect that he "may not be quite the criminal mastermind his reputation suggests".