"The Psychology of Time Travel" by Kate Mascarenhas‎ (Head of Zeus, 2018)

• Margaret (baroness), Lucille (black, from Toxteth), Grace and Barbara discover time-travel in 1967. After a few trips, Barbara has a breakdown. Was it a coincidence?
• In another time-line starting in 2017, Ruby Rebello, Barbara's grand-daughter is staying with Barbara. They get a hint that on 6th Jan, 2018, there'll be a time-travel related death.
• A third time-line begins on 6th Jan, 2018 when Odette, a Cambridge student born in the Setchelles who's a Toy museum volunteer in her vacation, finds a dead body in a room locked from the inside. Murder. She seeks trauma therapy with Ruby because she's having flashbacks.

The book flicks between these 3 time-lines.

In this book people can't go back any further than the moment of the time machine's creation, and no further forward than 2267 (a detail never explained). The UK has a monopoly on the fuel. A form of radio communication through time is possible. There are 3 main types of traveller - physicists, spies/entrepeneurs/scholars, and maintenance staff. "The Conclave" manage time-travel with laws that value divine judgement more than fairness - trial by ordeal etc. On p.113 it's explained that the maintainers can't be paid by the year, nor is it clear what currency they should be given.

Time-travel's part of the culture,

• Grace does a painting in reverse, the finishing touches first. It goes on show at the Tate Modern.
• Toys - "Candybox" - are on sale that make sweets disappear for a few moments by shifting them in time for a minute.
• As part of job interviews at The Conclave, interviewees time travel

but time-travellers have their own private culture too -

• "When you're a time-traveller, the people you love die, and you carry on seeing them, so their death stops making a difference to you. The only death that will ever change things is your own" (p.54).
• Young women go ahead in time to meet themselves soon after they first give birth.
• Jargon has developed. "Feeling angry with someone for things they won't do wrong for years is called zeitigzorn" (p.109). Non-time travellers are called "emus" (because they can't go backwards). "Infidelity committed with a past or future self was called me-timing" (p.145)
• The same woman from several times all meet for a pre-wedding hen do (p.85)
• Adultery across time is common-place
• When time-travellers get engaged their birth and death dates are engraved inside their rings
• "if you've heard about an incident for years, actually experiencing it feels like a release. We call it - Completing" (p.207)
• 'Sometimes,' Fay mused, 'I like watching people have emotions I don't feel any more' (p.214)
• By the 22nd century "psychology was a relic. It had largely been replaced by theological determinism" (p.186)
• "acausal matter" appears from nowhere. Maybe "time travel recreates an excess of energy that generates these objects" (p.229)
• After a partner dies, they're still reachable in the past, so is remarriage adultery? "Every other dead person was reachable by time machine, which made one's own death uniquely final and lonely" (p.273)

The writing can be quite dense, with observation, clues and information intermixing

She stopped at a second-hand bookstall. The bookseller was completing a crossword. 'Back again?' he said to Odette. His false teeth were a little too large. She smiled politely. He had confused her with somebody else. One of the book trays contained foreign language novels. She rifled through the French section, looking for something her mother, Claire, might like to read (p.37)

Subplots abound. Ruby is a lesbian. Her mother, Dinah, is going out with Henry, a church-goer. Ruby regrets trying to get Barbara to join her erstwhile colleagues at The Conclave when she learns that Barbara's tried to kill herself in the past. Ruby and Grace become intimate in 2017. Zach Callaghan, a journalist, has been investigating shady dealings within The Conclave with the help of a mole. Odette meets him, decides to apply for a job at The Conclave. Fay (Ginger's daughter) and Teddy get 3rd-person privileged attention on p.132. Teddy makes Fay juggle with his kidneys from the future.

Belief has to be suspended frequently - as much, but not as wittily, as for Hitch-hiker's Guide or Dr Who. When it suits the plot, people have trouble putting two and two together. It's as if the author wants Real people to be living in a Hitch-hiker's Guide galaxy. Cute ideas on one page wreck the plot elsewhere (not least, the locked room mystery shouldn't be a puzzle to anyone, given the prevalence of time-travel and toys that make sweets disappear).

A common piece of advice for SF/fantasy writers is to change just one feature of the world and keep the rest consistent. This book wants us to suspend disbelief in several ways -

• Science - time-travel is tricky. There are paradoxes to deal with. After 50 years there's no technological progress - how could Barbara, after decades away from science, get a bright idea that young scientists and future people didn't get? The book shows that a person from several different times can meet themselves. Potentially billions could?
• Society - all time-travel happens from one building in London. There's no curiosity by the public, no other countries wanting a part. Odette's surprised when at a job interview she time-travels. I'm surprising too.
Personality - What cognitive blind-spot could prevent Odette immediately suspecting time-travel was behind the locked-door crime? Why don't queues of people want to see the future? Couldn't The Conclave make lots of money?

Towards the end it becomes a whodunit. I realised I should have drawn a 3D diagram to work it all out. So Julie is Angharad's mother. Margaret's grandfather had the toy museum built. Odette watches a message delivered by Fay.

There's a Glossary (fun, though we've seen much of it already) and 30 pages of Psychometric tests set by the Conclave.

Other reviews

• Sarah Ditum (There are a few awkward details that emerge strangely late on in the novel, when both smooth plotting and the logic of time travel might dictate that they should be clear from much earlier on; but overall, Mascarenhas handles the challenge she’s devised for herself with remarkable deftness.)
• Zachary Houle (However, as much as I hate to say it for all the good that this novel does, this isn’t a terribly well-written book. ... there is a lot going on in this novel. I would argue that it’s too busy. New characters are introduced and then thrown to the wayside, making it tough to understand what’s really going on. There are also several plot holes and things that don’t make much sense ... However, the novel’s biggest sin is that it’s quite boring)
 
• Annabel (Appendices at the book’s end containing a whole series of psychometric tests for time-travellers shouldn’t be ignored either, they add a final layer to the story. ... Mascarenhas has created a great cast of women characters in the original quartet augmented by Ruby and Odette, and to have devised a fiendishly clever locked room mystery to drive the plot made this novel a real page-turner that got my full attention.)
• Ian Mond (Mascarenhas is fully aware of the rich history of the genre, and to this end, she provides the reader with a puzzle box plot, a whodun­nit told out of chronological order.)
• Ana Grilo (a heady mix of time travel thriller and murder mystery with a dash of a lovely (lesbian) romance and a lot of diversity. It is also thought-provoking - and often very uncomfortable, so trigger warning! - when addressing the topic of mental health.)
• Good reads