Over sea, under stone /
Illustrated by Margery Gill.
- [1st American ed.].
- New York : Harcourt, Brace & World, [1966, c1965]
- 252 p. : illus. ; 21 cm.
Three children on a holiday in Cornwall find an ancient manuscript which sends them on a dangerous quest for a grail that would reveal the true story of King Arthur.