This one is mixed, though let me say from the outset, it's worth reading.
The bad, or at least not-so-good?
The center of this mystery drains your energy, possibly in part because of the almost Tolstoyesque proliferation of characters - almost, because nobody in this novel has a half-dozen nicknames you have to keep straight. There is also a heavy and almost repetitive ladling of timetables and alibis that a more stringent editor might have pared down.
Too, you might get a bit tired of the way the New Zealand police force sucks up to Alleyn, especially since he seems never to be wholly on top of his form. (As another reviewer says, except in one letter from Alleyn, there's no Fox to act as an intelligent sounding board. When at his boss's side, Fox serves to reveal Alleyn's sharpness, and without Fox, much of that sharpness can't surface.)
The good side?
There are moments that bring the story to life. Amazon and the publisher have enabled the "search in this book" feature above: search on `fascination train' without the single quotes and read the page. Late-night, cross-country passenger train rides are rare in my country, the US, but I've been on a couple, and Marsh clearly has captured the essence.
Plus, the backstage world is well depicted - you get to see a little about how the technical side of theater lives and breathes. The novel revolves around a fabricated tech "accident" and there's a bit of foreshadowing that brings depth to a later statement, "when men are working aloft. I remember the stage-manager told me the [stage] hands always have their tools tied to their wrists." The reality of backstage is that when everything is perfect, nobody really notices - and when something goes awry, the stagehands could not feel worse.
There is also a crystal moment between Alleyn and Carolyn Dacres, a picnic excursion that the smitten Alleyn orchestrates to soften the usual grilling session. Here, Marsh expresses both the essential goodness (and grief) of the actress and the essential attraction of the New Zealand back country.
There are also memorably complex characters. Is it coincidence that surname of the Oxford-educated Maori physician, Dr. Rangi Te Pokiha, is about as close as you can get to "paheka," the Maori name for European settlers on the ranges of their land? And don't miss St. John Ackroyd, the acrid comedian.
And the last lines of the book, quoting a letter from Miss Dacres to Alleyn sent to him after all has been said and done, presents a touchingly human denouement.
I guess this is a roundabout way of saying, all Marsh is good; some are better than this; but this has fine moments.