The Shattered Stars
Bantam Books 
Synopsis: Moses Callahan has a debt-laden starship. Desperate for crew and cargo, he accepts a very shady cargo from a businessman and hires Deacon Halloran, a shell-shocked veteran of war to pilot his ship. The businessman turns up very dead but the cargo, a Bethe trigger able of catalysing a wide range of nuclear reactions, arrives anyway. Planning to hand it over to the legal authorities at the far end, Moses accepts it.
His engineer, 'Spooky' Tamura, is a telepath who has escaped the ministrations of the Annex, a mutual aid society of telepaths apparently run by sociopaths. She is visited by a node, a telepathic package which can simulate certain aspects of her teacher. The node sets up residence in her brain and informs her a far worse monster than any in the Annex, an outright psychopath named White, is using his node-ridden pawns to have the Bethe trigger brought to him. Since White is far more powerful than Tamura and Tamura is utterly expendable, the node proposes to teach Tamura in the hopes that technique will over come the self-trained White's raw power.
The henchmen purchase berths onboard the ship. En route, they use [Or rather the Node White has implanted in them] uses telepathic attacks to undermine Moses and drive him mad, to take the ship away from him. White has plans for the ship. Matters are made worse when Moses accidentally discovers Tamura is a telepath and he orders her to leave the ship when they land.
Tamura and Deacon then form an alliance. She helps him deal with his mental conditioning and he in turn can then access his combat skills, which the conditioning was supposed to suppress [due to namby-pamby officers worrying that Deacon's habit of automatically killing people who nudged him might reflect poorly on the military for having conditioned him to react like that in the first place]. White's henchmen attempt to stop Moses from turning over the Bethe trigger but are killed by Halloran and Tamura. Moses is kidnapped by White, but Halloran and Tamura rescue him. Halloran and White die in the firefight and telepathic battles. Moses and Tamura are reconciled and resume their captain-crew relationship.
I have fond memories of this book. It didn't really work for me in rereading, but I think I just was not in the right mood: The Shattered Stars is terribly derivative of previous action-oriented SF but so is a lot of SF&F I enjoy. My main criticism is that McEnroe doesn't really have a distinctive voice and there's nothing I can point to and say 'This is what marks McEnroe from Schmitz' for example [Well, there are distinctions, but Schmitz is the one providing them]. Perfectly satisfactory although not brilliant action adventure pulp SF.
I did raise my eyebrows at the use of a photon rocket in an atmosphere. Bet McEnroe never did the math on how much power that requires.
McEnroe wrote this book, two others in the same universe, two Buck Rogers books based on plot outlines by Niven and Pournelle and edited a collection of 1980s SF. After about 1985 he seems to have stopped getting published. No idea why: I bet the three Far Stars and Future Times books might do well as Baen reprints. The only problem might be the length: all three are quite short, probably too short for the modern market.
Next: Rite of Passage by Alexei Panshin [with quotations from e-conversation with the author]