Unfinished Crime — Helen McCloy

When Sara Dacre comes across a large red pendant at a twenty cent jewellery stall she is tempted to buy it - especially when she bumps into her friend Gerry Hone, who persuades her that it will brighten up her old grey taffeta.

But soon she finds herself at the centre of some strange events. On leaving the shop she and Gerry witness the scene of an accident - but nobody can agree what happened. And when Gerry takes her to an automat for coffee he goes to the counter to order - and never comes back ...

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