I was not too blown away by this one (did Thou Shell of Death raise expectations too high?). The humour here is sporadic, Nigel a tad too amateurish, and the resolution a little predictable. The problem with the author harping upon Nigel’s faultless verbal memory is that the reader is going to catch on at some point. That said, it is still a very good read, the chief delight being Mr. Grimshaw, whose ears wiggle "molto agitato", who utters delightful incomprehensibles like "hum-mum-chumble-yum." Blake is a cunning, judicious writer willing to forego all manner of vocabulary (on occasion) to great comic effect. Another instance is when Mr. Barnes "does complicated things with his eyebrows." Revolving ears (and eyebrows that do complicated things) are not to be found in most novels of this kind. Humour is, therefore, the chief delight in reading Nicholas Blake, and I find myself distracted from everything else.

There is also perhaps a sort of formula in his novels, but I won’t say more on the subject until I’ve read another one (which will be The Beast Must Die). 

Now from the film noir lens:

The comedy increases as the story wears on and reaches its highest point with the sudden introduction of Lily Barnes, whose part-Jean Harlow part-Greta Garbo appearance momentarily knocks the sandy colour out of Nigel’s hair. She is very briefly, and quite memorably, a femme fatale (I hope this isn’t just me obsessively looking at everything as having some cause-effect relationship with film noir). The primary reason I made this connection is because of the setting — a parlour so hot and overcrowded with ferns that it gives the impression of a tropical forest (does this not remind one of The Big Sleep?). The secondary reason is, of course, Lily herself. An extract from her introduction:

"Lily Barnes wore an old raincoat - and nothing between it and the ‘best Sunday undies,’ Nigel suspected."

She does not speak; she moos. By the time he’s leaving, Nigel finds himself telling her he’s married.