Basil Blackwell, 1943.
First edition, second isse. First issue is 1" thick and the second issue, 0.5" thick - both state only "First Published 1943" to copyright page. 8vo. Light blue boards with black titles. Pictorial dustwrapper. A very good+ copy. Clean boards with a few tiny spots to front board. Internally clean with a light occasional spotting to endpapers only. The very good dustwrapper is same as the first issue but obviously wrapped around a thinner volume; Nicking to extremities with some old strengthening to inside spine tips. Original price of 6/-net to front flap.
The fourth title in the "Secret" series. Mike, Nora, Peggy and Jack's summer holidays take them to Prince Paul's magnificent castle up in the mountains at Killimooin in Baronia; holed up in those mountains are a band of robbers who have intentions to kidnap both the children and Prince Paul.