With the exception of The Red Mist, all published Cthulhu Confidential scenarios use one of the three protagonists from the original campaigns. Does that mean that these scenarios work best when inserted into those campaigns? After playing and loving The Red Mist, we'd like to play another one, without the commitment of a full campaign -- but also leaving the door open, i.e. without the one-shot spoiling anything from any of the three campaigns.
Maybe if one of them is a prequel to its respective campaign, that would work as a one-shot? It is hard to tell without reading them, but if I read them and they do contain spoilers, then it'd be too late already...