It felt like another planet. I wondered: what if this was another planet? How would all these elements come together in a story? Eventually, this other planet became the Earth of the far future and I had to ask myself, what went wrong?

Colin Brush – 18 November 2025

The Back Flap

A debut sci-fi mystery set on an abandoned future Earth, featuring a twisty mystery straight out of a John le Carré novel, a group of larger-than-life characters who’d be at home in the work of John Scalzi, and a deeply weird and dangerous hyperdimensional entity to haunt the dreams of any reader of Kim Stanley Robinson.

Humanity is dying. Banished from the Earth, our descendants eke out lives in orbital habitats and moon colonies––and look with longing on our former home.

But Earth is deadly. Over hundreds of years, its oceans have transformed into an annihilating liquid entity––the Caul. Every living creature approaching its shores is irresistibly compelled to enter. . . and is never seen again.

Scientists, some of the few inhabitants left, work in facilities seeking to understand and stop the Caul. And scavenging the shores are the penitents—those who resist its siren lure.

Among them is penitent Mae Jameson, an octogenarian former Service agent who arrived on Earth thirty years ago to find her lover. When she encounters Siofra, a mute girl, wandering alone by the shore and returns her home, they discover the girl’s father, rogue scientist Carl Magellan, hanging from a noose. He’s been murdered. Unwilling to leave the matter in the hands of the facility Carl abandoned years ago, Mae takes Carl’s journals—which detail his obsession with the Caul and its mysteries—and sets about investigating.

In this page-turning, dual-timeline novel, both Mae and Carl’s quests for the truth put them at the center of a dangerous conspiracy. Someone believes they can use the secret of the Caul to shape humanity’s future, and they aren’t afraid to kill to keep control of it.

About the book

What is the book about?

It is set a thousand years from now when the Earth has been abandoned due to the oceans transforming into an attractive but annihilating liquid entity known as the Caul. A few (fool)hardy scientists study the Caul to seek ways of reversing the change. Alongside the scientists are the penitents, those who illegally came to Earth to enter the Caul (many worship it as a kind of god), but in the end chose not to do so. When Mae, an 81-year-old penitent and former policewoman, finds a young girl, Siofra, by the shore, she returns the girl to her rogue scientist father, only to find him dead. Fearing he was murdered, she takes the child home and sets about investigating his death. But there are those who want the secrets Siofra’s father uncovered about the Caul and they will do anything to keep them . . .

When did you start writing the book?

I came up with the original idea in 2004, after a visit to Dungeness, on the southeast coast of England. I made a few notes, but I was writing something else, and I’d only really manage any writing in brief between work on this other book (which I spent, deep breath, around fifteen years rewriting and revising, first alone and then with an agent, before we eventually shelved it). I sat down properly to write Exo in 2018.

How long did it take you to write it?

From conception to publication, 21 years. But I probably spent two years on it initially, but when my agent failed to sell it, I extensively revised it, which took another year, before it finally sold.

Where did you get the idea from?

The initial idea came from visiting the seaside wilderness of Dungeness, which consists of a a triangular pebble plain, a few houses and shacks, a number of beached fishing boats, two lighthouses, a decommissioned nuclear power station, and the sea on two sides. It felt like another planet. I wondered: what if this was another planet? How would all these elements come together in a story? Eventually, this other planet became the Earth of the far future and I had to ask myself, what went wrong?

Were there any parts of the book where you struggled?

A third of the original story was set in a facility that studied the Caul, exploring the relationships between those characters and detailing a conspiracy. This was the least successful aspect of the tale in the rejection responses we received. When it came to revising the novel, it made most sense to cut it out almost entirely. It was a relief, and made the story far simpler.

What came easily?

The remaining two point of view characters, detective Mae and scientist Magellan, always came easily. Mae was a character as least like me as I could make her: an old woman who was difficult, uncooperative, distrusting, closed, prickly (but these are also her strengths). I just had to get her to act in the opposite way to my own inclinations to always get along with people. Magellan, a man in his fifties, was much closer to me, but his success as a scientist had made him arrogant – something his wife consistently attempts to point out. As a result, he is an unreliable narrator. He should appear straightforward but reading between the lines should tell another story. This wasn’t hard to write, but I can’t know how successful I was until I hear back from readers.

Are your characters entirely fictitious or have you borrowed from real world people you know?

The characters are entirely fictitious.

We all know how important it is for writers to read. Are there any particular authors that have influenced how you write and, if so, how have they influenced you?

All of the writers I have read have influenced me in ways I probably don’t even notice. Recent writers who have taught me so much include: Iain Banks, Terry Pratchett, David Mitchell, Ursula K Le Guin, Kate Atkinson, Dorothy Sayers, Sandra Newman, Michael Moorcock, China Mieville, Barbara Pym, Aliya Whiteley

Do you have a target reader?

I write for myself, but I am always thinking of the poor reader trying to make sense of the story and the world (this comes from being a publishing copywriter, where you try and write to the reader, rather than expecting them to come to you). I like books that start small and then expand dramatically, the world or story suddenly much bigger or more significant than you initially believed.

About Writing

Do you have a writing process? If so can you please describe it?

I tend to write rough first, following a vague plan. Then I revise repeatedly until I’m happy. I need to know the structure of the story before I begin writing, though that might change. (It always changes. I waste so many words.)

Do you outline? If so, do you do so extensively or just chapter headings and a couple of sentences?

Yes, there is a plan. It can be detailed in places or quite light. I’m never facing a blank page when I write. I always know what needs to be in the next scene I’m drafting, from beginning to end. But as I write the story starts to evolve. I often get halfway and realise what I want to do has changed so significantly I need to go back to the beginning and rework it. (See my earlier answer about spending fifteen years on another project!) In my day job, I’m frequently called on to redraft copy, so this is nothing new. Never let your love of your words get in the way of making the book better. Kill your darlings, as they say.

Do you edit as you go or wait until you’ve finished?

I work in sections. I’ll write in rough and then work that up until I’m reasonably happy, then on to the next section.

Do you listen to music while you write? If yes, what gets the fingers tapping?

Only if I’m writing somewhere there is a conversation going on that I can’t get out of my head, like on a train or in a café. It needs to be music with no words. Classical is good, but sometimes it can’t drown out the conversation.

About Publishing

Did you submit your work to Agents?

I sent it to the one agent I’d been working with on another project for many years.

What made you decide to go Indie, whether self-publishing or with an indie publisher? Was it a particular event or a gradual process?

They wanted to publish the book, no one else did. It was as simple as that.

Did you get your book cover professionally done or did you do it yourself?

The publisher did it using a freelance designer.

Do you have a marketing plan for the book or are you just winging it?

There is a marketing plan that my publisher has created and I’m working with a publicist they have hired who is finding me venues to talk about my book, such as this one.

Any advice that you would like to give to other newbies considering becoming Indie authors?

Never give up. Keep trying all avenues, agents, publishers, independents. Even got it alone. These days, so many authors (particularly in science fiction and fantasy) start out self-publishing and their success sees them picked up by traditional publishers and agents. But also keep working on your writing. I’m a professional copywriter. I can write sentences and paragraphs and articles but I’ve still so much to learn about structuring a novel.

About You

Where did you grow up?

I was born in Scotland and raised on the Channel Island of Jersey.

Where do you live now?

I live in St Leonards on Sea (the west of town to Hastings’ east of town) on the English south coast.

What would you like readers to know about you?

I’ve worked in the UK book trade for over thirty years and I’ve worked at what is now the world’s largest trade publisher for the last 25 years, writing jacket copy on over 5,000 books. But working in publishing hasn’t noticeably helped me get published. I needed to learn my craft at the book level, and I still do.

What are you working on now?

It took a long time to sell my book Exo and before it was sold my agent advised me that the market looked rather different to the kind of thing I was writing, so I switched to writing something rather different. This story is set in a brutal school for troubled or gifted teenagers as they are instructed to play ‘the bead game’, gradually coming to understand its sinister purpose.

End of Interview:

Get your copy of Exo from Amazon US.