They are staying with their Mother and baby sister Bridget in a new location, Pin Mill on the River Orwell upstream from the ports of Felixstowe and Harwich and are in Suffolk to meet their Father, Navy Commander Ted Walker who is returning overland from a posting in Hong Kong (then a British possession) to take up a new posting at Shotley.

The four eldest Walker children help Jim Brading, who has been given the sailing cutter Goblin by his uncle, make her fast when he misses his mooring buoy.

So, leaving the children aboard the anchored Goblin Jim rows ashore in his dinghy, the Imp, to catch a bus to a garage in order to fill a petrol can.

Aboard the drifting boat, John decides that it is safer to hoist the sails and go farther out to sea rather than stay near the shore among the sandbanks and shoals of the estuary, with the risk of being wrecked in the fog.

They are then nearly run down by a ship as the navigation lights are out of paraffin - Titty improvises with a powerful torch and a red translucent plate.

Their father sends some carefully worded telegrams to Pin Mill, and as the children sleep, sails the Goblin back to England the following night.

[1] Helen Alice Howard, of the Lexington Herald-Leader, agreed with this, and added that despite the conceit—of blowing all the way across the ocean—the convincing writing of the author makes the reader accept it as a possibility.

[2] The Brooklyn Eagle's review believed it the work's "exciting adventure" would make it appeal to young readers, and also complimented the books "wholesomeness".

[3] Francis Broaddus Jr., writing in the El Paso Times, opined that the action was slightly faster than was normal for the series, which he thought would make the book more appealing for its target audience.