Benny is dying as her brain destroys itself from the inside. She enlists the help of the guy she met in The Mary-Sue Extrusion to prevent another Dellahan god going on the rampage. Said guy had once been to Sharabeth, the Fractured Planet. At no point in this novel does anyone actually return there.
Professor Bernice Summerfield.
Chris Cwej, in his second body (mostly in disguise as Roland Forrester throughout the novel).
The Mary-Sue Extrusion is the introduction to our narrator character and also introduced the Mary-Sue procedure that Benny underwent. Tears of the Oracle revealed that said procedure began the disease that is now destroying her brain.
There are, unsurprisingly, loads of references to The Mary-Sue Extrusion. I'm not going to note all but the most salient. Basically, if you don't know what the reference is to, it's to that.
Back cover: "Nothing is ever simple and nothing ever ends. Feed some drugs to laboratory rats and, two hundred generations down the line, the monsters start being born." Not only is this a direct quote from Pg 240 of The Mary-Sue Extrusion, it's also, so far as I can tell, irrelevant to the plot of this novel.
Pg viii Apparently, Benny has a descendant called Eleanore Vita Hydrant Summerfield-Kane. Oh dear.
Pgs 1-2 are a direct, full quotation from The Mary-Sue Extrusion, which themselves open with a near quotation of something from So Vile A Sin as a kind of double-bonus theft.
Pg 19 "'My name's Kara,' the woman said as I tried and failed to fight against the restraints holding me [...] 'Kara Delbane.'" Possibly related to Katherine Delbane in Heart of TARDIS (and they may even be the same person, given that Kara is an Artificial Personality Embodiment).
Pg 21 "A feisty young kid picked up by an eccentric time-travelling alien to serve as his companion as he adventures through time and space, that sort of thing." The fictional backgrounds given to the various Artificial Personality Embodiments (APEs) include this one, which is blatantly Sam Jones from the EDAs. It's quite clever actually, as the whole point of Sam is that her 'feisty young kid'-ness is basically a fiction.
Pg 22 "This is what's known in the Catan Nebula manufactories as their 'break-out lifetime'." The Catan Nebula was where our narrator was recreated, as detailed in The Mary-Sue Extrusion.
Pg 25 "My bloodstream stores enough oxygen to survive fifteen minutes of strenuous effort in a vacuum and, at a pinch, in an appropriate environment, I can bypass my primary respiratory system entirely [...] and a cardiovascular system that might not actually include what the promotional literature calls a 'second heart', but does have something that serves as the equivalent of a fuel-injection pump." Very specifically set up to resemble the physiognomy of the Doctor.
Pg 28 "I'm ARVID. I own you. Welcome to the Oblivion Angels." An ARVID was mentioned in Ship of Fools.
Pg 29 "I'm here to tell you, naturally, that the New Frontier Adventures and complete and utter toss." This is the sort-of in-universe version of the NAs, reimagined as pulp nonsense and sold in airports all over the twenty-sixth century. They feature Berni Summerfield as their lead character and were first mentioned in - yes, you guessed it - The Mary-Sue Extrusion.
Pg 30 And there is a summary of the events of that novel here on this page, should you choose to peruse it.
Pg 32 "Yes, that Irving Braxiatel. The one with the New Collection." The Braxiatel Collection, first mentioned in City of Death, extrapolated upon in Theatre of War and recently in the process of being moved to Asteroid KS-159 as detailed in Tears of the Oracle.
Pg 33 "Braxiatel was the sole and freehold owner of this concern, and had been one of the guiding lights within the now-destroyed University on Dellah." We witnessed said destruction in Where Angels Fear.
Pg 36 "Don't tell me Prince Jimbo's risen from the lead-lined coffin or something." The Mary-Sue Extrusion once again, and, in Prince Jimbo, one of its more offensive stereotypes. There's also reference to the Thanaxon Council, also from that story.
Pg 43 "It's what the mind believes on the deep subconscious level that counts." The approach needed on Sharabeth mirrors the way the majority of characters saw the universe in Sky Pirates!
Pg 51 "[...] in what looked suspiciously like dried blood without the platelets that would make it clot instead of dry, but which I later learn to be cold tea." Braxiatel writes documents in cold tea, as the Doctor did in Warlock (and, based on that, The Curse of Fenric).
Pg 69 Just a note to say that I struggle to see Benny using the word 'sybaritically' as she apparently does here. Not as bad as what Chris does later though.
Pg 75 "The thing inside me has kindly given me several months to set my affairs in order." In Tears of the Oracle, this would have been way too generous, as it appeared she had about a month to live. However, towards the end of that novel, it's noted that Benny's problem is slowing down, so this tracks. Presumably, said slowing down was added by Justin Richards when he read the drafts of this book.
Pg 96 "Investigator Roland Forrester." Chris's nom de guerre is, fairly obviously, based on Roz's name (Original Sin to So Vile A Sin; a life enclosed by sins, it would seem).
Pg 100 "I can't give you a clinical diagnosis or anything, but it's inside her head and it's killing her. She's dying." Benny's brain disease was caused in The Mary-Sue Extrusion and revealed in Tears of the Oracle.
Pg 154 "It wasn't like the cases of possession I'd seen on Dellah and Thanaxos. The entities that subsumed their living hosts to become embodied gods operated in a different way." Where Angels Fear and The Mary-Sue Extrusion, although this description doesn't quite square with Where Angels Fear.
Pg 158 Chris Cwej saying "You're fucking nicked, me old son" doesn't exactly seem in character. Yes, told you that was coming.
Pg 192 "And then I'm gonna start on Finnegan's Wake." Also mentioned in The Mary-Sue Extrusion.
Pg 216 "You see those bubble circuits on the inside?" Possible a reference to bubble memory from Logopolis.
Pg 223 "The light it cast seeming to pulse and swirl over it, producing a scintillating and maybe even coruscating effect." Dave Stone has previously massively overused the word 'coruscating' in Sky Pirates!.
Pg 233 "Now, Cwej, apparently, was once a real cop [...] a member of the Church of Adjudicators on Earth, with real cop instincts." We knew this, of course, from Original Sin et al.
OLD FRIENDS AND OLD ENEMIES
Our old friend, the unreliable narrator of The Mary-Sue Extrusion, this time telling us two interlinked narratives.
Box, his computerized friend, late of The Mary-Sue Extrusion as well (and Star Cops before that).
Mira, from The Mary-Sue Extrusion, although you will be hardly shocked by this revelation of her literary origins by now.
Absalom Sleed is one of the Dellahan gods, so we may have met him before. He was forcibly removed from Dellah and thrown back in time so that he could be on Sharabeth some years before her appeared on Dellah. Belief in him resulted in him becoming an archetypical 'Villain', doing villainous things for the sake of being villainous. As such he, once again, fits in the with the awareness of its fictional narrative trope that typifies the Benny NAs, particularly at this point.
NEW FRIENDS AND NEW ENEMIES
Craven, an APE.
We meet some creatures described as 'basically human monsters', which is possibly clever and possibly really lazy. They only function as a unified pack when the mind in charge of them is active.
A nasty creature with glowing red eyes, jagged claws and something of a murderous intent.
Creatures called pararats, although we've no clear description of what they look like.
In the flashback narrative, the planet Sharabeth, a planet near to Dellah. Most of the action here takes place near the major population centre "'Wiglixix' or something", which sounds like a mispronunciation of somewhere named by the People. Which, in the context of the way things turn out, is quite clever actually.