The Doombolt Chase

Plot summary

During a night patrol in the Bristol Channel, Commander David Wheeler receives a message encrypted in Spens Code, unknown to Navy operators. He then deliberately rams and sinks a small fishing vessel. Court-martialled, Wheeler offers no explanation to his defending counsel Commander Jeffrey Vallance or his son Richard. Richard investigates with friends Lucy and junior seaman Pete, who witnessed the incident. Richard knows the Spens Code was created by former Naval Intelligence operative Hugh Spencer, a friend of his father living in Braxtet. The trio sails Wheeler's yacht, pursued by Navy watchdogs. To save time they enter the Navy's Forbidden Zone, encountering a radio-controlled boat with strange aerials. At Spencer's house they find him missing and signs of struggle. Clues lead to the word "Doombolt" and a map overlay of the Bristol Channel with marked points, including Scudmore manor. There they find heavy guards wearing silver suits and helmets—protective gear against ultrasonics—and witness a demonstration of a new superweapon directed by Doctor Franz Bayard.