The Times reviewed the work in its issue of 9 December 1930, saying that, "Mrs Christie steers her play with much dexterity; yet there are times when it is perilously near the doldrums. Always it is saved by Hercule Poirot, the great French [
sic] detective, who theorizes with the gusto of a man for whom the visible world hardly exists. He carries us with him, for he does not take himself too seriously, and he salts his shrewdness with wit. For a ruthless investigator he is an arrant sentimentalist; but that is one of the ways in which Mrs Christie prevents her problem from becoming tedious. Mr Sullivan is obviously very happy in the part, and his contribution to the evening's entertainment is a considerable one. Mr Boxer
Watsonizes pleasantly, and Miss Joyce Bland, as a young lady who must wait until the very end before knowing a moment's happiness, contrives to excite our sympathy for her distress. The remainder of the cast is rather serviceable than exciting."
The Observers issue of 14 December 1930 contained a review by "HH" in which he concluded that, "Miss Agatha Christie is a competent craftsman, and her play, which is methodically planned and well carried out and played, agreeably entertains."
The Guardian reviewed the play in its issue of 10 April 1931. The reviewer stated that, "Miss Christie knows the ropes, keeps to the track, sets her Herculean protector in defence of innocence, and unmasks the real villain at eleven o’clock. One must be something of a ritualist to find enchantment in such matters. Mr. Francis Sullivan makes a large, guttural, amiable sleuth of the sagacious Hercules . He is wise not to imitate Mr.
Charles Laughton who gave us such a brilliant study of the Belgian some time ago. He makes his own portrait and does it with a competent hand." The reviewer praised others in the cast by name and concluded, "the company conduct themselves with a proper sense of the ceremonial involved in a detective play. But it is surely permissible to be surprised that adult people can be found in fairly large numbers to sit undismayed through the execution of such ritual as this." Two days later,
Ivor Brown reviewed this second production in
The Observer when he said that, "If you are one of those playgoers who are eternally excited by a corpse in the library and cross-examination of the family, all is well. If not, not. To me the progress of detection seemed rather heavy going, but I start with some antipathy to murdered scientists and their coveted formulae. Black coffee is supposed to be a strong stimulant and powerful enemy of sleep. I found the title optimistic. "
The Times reviewed the play again when it opened at the Little Theatre in its issue of 13 May 1931. This time it said that, "Its false scents are made for the triumph of the omniscient Belgian detective, complete according to the best tradition with unintelligent foil; and if they appear sometimes to be manufactured with a little too much determination and to be revived when they seem most likely to be dissipated, they may be allowed because they just succeed in maintaining our sympathy with distressed beauty and our interest in the solution of a problem. Though much of the dialogue is stilted, the complacent detective has an engaging manner." ==Credits of London production==