Did the twelfth member of the jury know something the rest did not...?

Classic crime from one of the greats of the Detection Club

Circumstantial evidence was as good as proof in the trial of Viola Ross. Everything pointed to the conclusion that this beautiful woman had smothered her wisp of a husband. But the twelfth juror, Richard Arnold, would not agree. Perhaps he knew something which the others didn''t - perhaps he only guessed.

When a retrial is ordered, Arnold sets out to conduct his own investigation. But soon he is faced with three attempts on his life.