Along with Bill Cunningham, who appears later in the book, the children manage to expose a ring of spies led by the threatening Scar-Neck who are working against the UK Military service.

During the holidays, they live with Philip and Dinah's mother, Allie at Spring Cottage which she borrowed from her friend (no longer set in Scotland as in the original novel).

In episode 2, the four youngsters make friends with Tassie, a mysterious gypsy living in the woods with her mother, who is threatened by Sam, nicknamed Scar.

Towards the series’ end, Aunt Jane visits the children, as well as Bill Cunningham, whom Allie met during the convention at the Military service in the opening episode.

Three years later,[3] commenting on the updates which had seen an anti-tank device and the SAS included in the storyline, Anna Home (former head of children's programmes at the BBC who had been at TVS earlier in the 1980s) mentioned that Blyton "suffer(ed) from being neither truly period nor modern; it is difficult for writers and actors to know whether to retain the language and accent of the period or try to update it", and suggested that the dramatisation had not been "particularly successful".