By John Dickson Carr.
November 11, 2013):
I don't want to go into too much of the plot, but you should know that there are two major crimes here. One, taking place in France, is that impossible murder on a tower in France. Six years later, in England, some of the people involved in that first case find themselves thrown together - and there is another murder attempt.From THE SATURDAY REVIEW (March 30, 1946), archived here:
Stab wound kills man in medieval French tower. Girl almost scared to death in England. Enter Dr. Gideon Fell . . . - Another impossible crime, with adroit supernatural embroidery, cannily unravelled by Dr. F. in deft combination of shivers and skilful sleuthing. - Verdict: Required reading.