Although a decade passed for Norton’s fans between the third Solar Queen novel (1959’s Voodoo Planet) and the fourth (1969’s Postmarked the Stars), for protagonist Dane Thorson, the events of this book Postmarked the Stars, follow right on the heels of the earlier three.
Dane’s appointment as temporary cargo chief on the Solar Queen, replacing a superior on holiday, seems like it should be a good thing. All it does is paint a great big target on poor Dane. Ne’er do wells are plotting to use the ship for nefarious purposes. This becomes obvious when Dane, having set out to pick up a parcel for transport, wakes up from a drugged stupor in an unfamiliar room. When he staggers back to the Solar Queen, he finds that he has been replaced by a look-alike.
Temporarily. The look-alike in fact was in such terrible health he had no business trying to travel; he dies of an unexpected heart condition even before Dane gets back to the Solar Queen. There’s no way to ask him what he was up to. But that’s OK; the results of the doppleganger’s shenanigans are revealed in short order.