Published in 1977, this is a classic, well-plotted thriller, with a right touch of gritty realism and very little of the sleaze to come in future McBain's novel.
The sarcastic title refers to the killing of three blind people and the first murder is the key to the plot, dutiful investigated by Carella, still working as the main character of the series and he's only briefly supported by Meyer and Hawkes. McBain let us know that Carella is a good cop, reliable, strong, compassionate and tough when needed, but also not the smartest of the bunch.
For anybody with even little imagination, it will be obvious where Carella should look for the vital clue, but it takes a very long time before Carella actually gets there, all the while investigating the past nightmares of the victim (which will also be useful).
On a side note, and as a dutiful reader of the 87th Precinct's stories, it is disappointing to note how McBain grew into the "dirty old man" stereotype with each following instalment. As mentioned, here the sleaze is contained into the short mention of catalogs for "marital aids".
By 1990, whole 87th novels dealt with satanic orgies, raped prostitutes, graphic details of all sorts of couplings, prostitutes stake-out, Vice squads exploits, etc... (McBain seemed to have developed a thing for prostitution).
I am not sure if life in the Big Bad City got more perverted, or if it was just McBain, increasingly cynical, but also savouring the dirt.