I first discovered books by Rosemary Sutcliff when I worked as a children's librarian in the 1960s and remember enjoying her books. Although the books were written for older primary / lower secondary age readers they can be enjoyed by adults too. Rosemary Sutcliff obviously enjoyed history, particularly Roman history, and this is the setting for her novels. Eagle of the Ninth is the first of three of her books about Roman Britain, the other two being The Lantern Bearers and The Sword at Sunset. In the FutureLearn course that I did last year about Hadrian's Wall, The Eagle of the Ninth was often mentioned by participants in forum discussions. I therefore decided to read the book again.
Marcus Aquila was appointed as Centurion at a fort on Hadrian's Wall. He is a long way from Rome but he is following a family tradition as his father had been with the Ninth Legion that mysteriously disappeared when Marcus was a young boy. Marcus quickly settled into life on the Wall until the fort was attacked by local tribes and Marcus was severely injured. No longer able to remain in the army he initially stayed with his uncle at Calleva. When he eventually is able to walk again he set off with Esca, a former slave, to travel north to the other side of Hadrian's Wall in the attempt to discover the fate of the Ninth Legion and to locate the Eagle, the Legion's symbol.
Marcus's quest is an exciting story but what I appreciated was the description of life in Roman Britain encouraging the reader, for a short while, to experience what the characters in the novel are experiencing. Rosemary Sutcliff also examines the relationship between Marcus and Esca who is a Briton of the Brigantes tribe. Esca had been Marcus' slave but before they set out on the quest he is freed and once the two travel past the Wall it is Esca, with his knowledge of the area and the people, who often makes decisions.
Eagle of the Ninth was published in 1954 but has stood the test of time. Charlotte Higgins wrote a long article about the book in The Guardian in 2011, about the same time that a film, The Eagle, based on the book was released.
Postscript: I have just watched the DVD of the film, The Eagle, made some years ago and supposedly based on Rosemary Sutcliff's book. There was plenty of action but not a lot of resemblance to the story in the novel - still I guess you expect that in films of books.