The four children have longed all their lives to visit Tantamount, a castle on the Cornish coast, built by their great-great-great-grandfather.

Only when the children begin to explore do they realize that despite being built and furnished in magnificent style, the castle is suffering from decades of neglect.

Writing for the Chicago Tribune, Madeleine L'Engle deemed Richleighs a "beautifully wrought Gothic tale", adding: "Miss Willard has already shown herself to be one of the finest writers for children today, and in this book her talent shows new strength and depth.

"[2] The Saskatoon Star-Phoenix said, "[This] Victorian atmosphere story...is illustrated in a Dickenson manner which will restore some of the old Christmas spirit to the young of the present days.

"[3] Clarice Bosacker of the Albert Lea Sunday Tribune remarked, "[The adventure in this book] all combines to make exciting reading for the 12-year-old and up.