Sixwhits Press, 2025, 279 p. Reviewed for ParSec 15.

Everyone experiences a multiplicity of worlds, for modern science tells us that this is a prerequisite for consciousness. However, for those who are not entangled, they experience such a narrow slice of all the realities that all seem identical, so it feels like a single universe. The day-to-day experience of the unentangled is one of many worlds, but a thin, uniform one.
So goes an extract from The Measurement Problem, A Guide to Entanglement by one A K Amari, quotations from which precede each chapter of David Whitmarsh’s novel of the same title. This imagined non-fiction work is a handy device for the novel’s author to provide background and context without it jarringly obtruding into the text. Our narrator, Detective Inspector Lewis Drake, is reading it (intermittently) to gain some insight into the world of the entangled, people who can experience the multiple worlds, a group he abhors since his sister Alice is in The Grange, a care home, after being given the implicitins which promote entanglement, with results which incapacitated her.
The action takes place mainly in a future London beset by rising sea levels, with a flood defence wall surrounding an area from which people are given encouragement to leave, in the long aftermath of a damaging virus war. Transport in this world seems to be by apparently driverless cars effortlessly on call to the public, though the rich, as ever, have their own provision. Implicitins were developed from research into CM-2057-phi-kppa, a virus that robbed people – like Drake and his sister – of memories from before their infection.
Exposure to implicitins can be benign or lead to cerasthesia, where the mind is overwhelmed by overlapping sensations from the many worlds. Their various forms, produced by the firm VirGenTech, range from alphas through betas, gammas and deltas and give access to memories/sensations from increasingly further back in time according to which has been taken. Alice’s treatment for cerasthesia in The Grange has heavily involved Drake both emotionally and financially and led to estrangement and separation from his wife. Lost in the other worlds, Alice has occasional reversions to the more benign Omega State but more generally presents as unaware of her immediate surroundings.
We start, though, on the day Drake is killed. In Marek’s café, an establishment with a signature ill-fitting door which scrapes noisily when opened.
Except of course, he isn’t. Killed, that is. Not in our narrator’s world anyway, but certainly in one of the multiplicity of entangled worlds. “Our” Drake does experience a feeling of dread, however, as sensation bleeds across from that universe.
In the wake of that he is assigned to investigate the murder of one Roger Wyndham, presumed to have been shot by a criminal organisation called Rdeča Kremplja, or Red Claw, run by a shadowy individual known as Vidmar, and the thriller plot, with attempts to frame Drake for that murder, kicks in.
Solving it all necessitates the usual detective novel contretemps with superior officers and agents of the state, not to mention encounters with Red Claw minions, kidnappings, betrayals and narrow escapes, with Drake needing to take implicitins himself to access as much information from the many worlds as possible in order to give him the edge. Recovery of the records inside a machine called Regenesys 5101 which can edit DNA sequences and be used to change identity also proves necessary.
Apart from a tendency to spell out acronyms, both police and otherwise, Whitmarsh handles everything well. The slipping from one reality to another as Drake falls under the implicitins’ spell could have been a source of confusion to the reader but isn’t. All in all, Whitmarsh’s The Measurement Problem (as opposed perhaps to A K Amari’s) is an enjoyable enough SF/crime mashup.
The following did not appear in the published review.
“time interval later” count; substantial.
Pedant’s corner:- focused (several times; focused,) plus points for ‘whence’ used correctly, “a hairdressers” (a hairdresser’s.) “I wracked my brain” (I racked my brain,) “DI drake” (elsewhere always Drake.) “There were a string of voice messages” (There was a string of.) “Drake street” (Drake Street,) “outside of Cambridge” (no ‘of’, just ‘outside’,) “she’d drank me under the table” (she’d drunk me under the table,) “as good a guess is any” (as good a guess as any,) canvasses (canvases, please,) focussing (focusing,) “but the timing their appearance” (the timing of their appearance,) “latching onto to Alice” (no need for the ‘to’,) “Alice had invited us too” (invited us to,) “span off” (spun off. Two more instances of ‘span’ for ‘spun’,) protestors (protesters,) unfocussed (unfocused,) disk (disc,) “Soames’ answers” (Soames’s,) a new sentence begun with a lower case letter (x2,) imposter (x2, I prefer the spelling impostor,) Soames’ quarters (Soames’s,) “Regensys 5101” (elsewhere always ‘Regenesys 5101’,) “Sergeant Reynolds’ eyes opened” (Reynolds’ x3; ‘Reynolds’s’,) sat (sitting,) stationery (stationary,) “where Tamboli’s plants” (were Tamboli’s plants,) a question not given a question mark, “a drainage grill” (a drainage grille.) “It did me good, seeing him uneasy, relaxed me” (the second comma needs removed,) a missing opening quotation mark at the beginning of a piece of direct speech.