Orphaned Isabel is travelling back to England from India where she has lived all her life. She is in the care of Mrs. Colonel Hartington-Davis, who is travelling home with her children, Letitia and Horace. Isabel is different in that she does not seem to like anything or anyone except writing about them in her notebook. One night out on the deck she witnesses what she thinks is a murder. Isabel is not alone in seeing this however, as Sameer has seen it too and the two children decide to become detectives and solve the mystery of who has been murdered and by whom. Fortunately for them they are travelling on a mail ship with fewer passengers than on a larger vessel. But Letitia has also witnessed something amiss and the two girls, who are so very different, join with Sameer in a race against time to uncover the miscreant before the ship reaches Suez where he/she would have the opportunity to go ashore.
This is a very entertaining story with three very different characters; Isabel who is definitely a loner, Letitia very pretty and charming, and Sameer, another outsider in that he is Indian, travelling with his father, an eminent scientist. The story is told at quite a pace mirroring the need for speed before the ship reaches the first port, with humour, and also near caricatures of the adults on board, although this will be lost on most readers. The author does touch on the difficulty of Sameer, an educated Indian, who at that time would not have been accepted into the British society of the 1890s. It is difficult to see how Mrs. Hartington-Davis, presumably the wife of the Colonel of the Regiment, would have accepted her daughter being friends with him, especially in such a small gathering of Britons going home from India. The plot does get complicated at the end of the story and seems rather rushed which is a pity, as it is a very readable.
The author talks of her story as a prequel to The Secret Garden by Frances Hodgson Burnett, a book of its time, but as the heroine is not called Mary it is difficult to see the connection , except in so far as Mary travelled home from India by herself, and this mystery adventure stands alone in any case.