Ghastly covers books had in those days. The plot is good though, like all Agathas. This one I haven't read as often as my favourites, but it's well worth a re-read.
From the blurb: "When a house party gathers at Gull’s Point,the seaside home of an elderly widow, earlier events come to a dramatic head. As Superintendent Battle discovers, it is all part of a carefullylaid plan—for murder."