Paper looks calm. That is one of its tricks. A date. A signature. A box ticked. A cause entered beneath a heading. Everything behaving.

An Improbability of Puffins contains a lot of paperwork. It starts with an inheritance in a will, followed by probate documents, delays and caveats. We soon uncover lighthouse logs, old maps, records and charts. Council minutes, official paperwork, Coroner's notes. Archive files with old handwriting pressed hard enough to leave marks on the sheet beneath. It also contains radio tapes, photographs, recordings and footage. All different ways of saying: this happened. 

Except records are made by people. People choose the heading. They decide which sentence belongs in the minutes. They decide whether an account sounds credible. They choose fog instead of clear weather, accident instead of uncertainty, absence instead of a name they cannot explain. That does not make the record worthless. It makes it human. The question running beneath the book became: who gets believed?

Ellie works with sound because voices resist tidiness. A breath remains. A hesitation. Someone pauses before the important word. Thirty seconds of room tone can tell you what a transcript has removed.

Beryan approaches the same problem through images. Frame by frame. Date against date. Look again.

Karensa has another archive altogether. She remembers. The family kitchen holds what official paper never asked for. A photograph, a coat, an old lullaby, a phrase in an unknown language, the way somebody once took their tea.

Writing the novel made me increasingly interested in the space between those forms of evidence. Between public record and private memory. Neither perfect. Neither disposable. Sometimes truth survives because somebody filed the paper. Sometimes it survives because somebody refused to throw away the biscuit tin.

I started with a woman returning to an island and the sea she had spent years avoiding. Her absence is highlighted by family, and it's made clear she hasn’t been back for several years …

Ellie Pentreath had left. She made the choice and ran from Scilly at the same age as, Karensa, her sister, had lost the choice to go and been forced to stay. Between that sits a world of difference, of opportunities missed or of family lost. It’s everything that can accumulate when one person escapes and another becomes responsible for what remains: old promises, missed visits, burnt toast, childhood, resentment, responsibility and duty.

Even though Karensa is Ellie’s big sister, she was the one who raised Ellie. Their relationship is more like parent and child than siblings. Ellie’s arrival forced adulthood on Karensa; did she have a choice?

Karensa has spent years making things that can be held. Bread. Tea. Packed bags. A warm room. Ellie makes recordings. She catches voices before they disappear. One sister keeps people alive through the ordinary. The other listens for what the ordinary has missed.

Then there is Beryan, Karensa’s teenage daughter. Fifteen, camera in hand, unimpressed by adult evasions. She loves them both, which means she has very little patience with the stories they tell themselves. Where Ellie hears, Beryan frames. Where Karensa protects, Beryan asks what that protection has cost. That interested me far more than writing three generations who simply understand one another. They don't. They interrupt. They withhold. They make tea instead of apologising. They use the wrong words. Sometimes they use no words at all.

Much of An Improbability of Puffins happens around impossible things: a lighthouse, wrong lights, missing minutes, old records that refuse to behave. Yet some of the hardest scenes to write contained none of those things.

Three women. A bakery table. A photograph face down between them. A kettle nearly boiling and Karensa’s infamous saffron buns. Family can hold far stranger weather than a lighthouse. And sometimes staying in the room is the bravest thing anybody does.