The Unseen World

Ada Sibelius is twelve, painfully shy, and has never attended school. In 1980s Boston her father David, a brilliant and socially awkward single parent, runs a university computer science lab and takes her there every day. Her closest confidant is ELIXIR, a program David built to learn human speech through conversation.

Then David's memory begins to fail. As his mind goes, his past unravels too: nothing records the man he claimed to be, and no legitimate account explains how Ada was born. With her father unable to care for her, she is taken in by his colleague Diana Liston and Diana's sons.

David leaves Ada one thing while he is still lucid, a coded file. She spends years trying to work out what it means.

The story moves between three periods: Ada's adolescence in Boston, her adult working life in San Francisco, and David's own buried youth. The pace is slow and methodical, closer to an unravelling than a thriller. Underneath run questions about how much memory a machine can be taught to hold, what disappears when a mind declines, and how far a child is allowed to know a parent.

The open question is whether the file can lead Ada to the father who raised her.