It all begins innocently enough when the narrator, Miles Adler-Hart, is 9 and jacks a spare phone into the house line so he can find out about Survivor, a TV show his mother won't let him watch.
He never learns what the show is about but what he does overhear reveals just how many holes there are in his knowing of her, and filling those gaps becomes an obsession.
At first his main worry is how she is coping after their father leaves, but it really becomes serious when his mother's new boyfriend, Eli, enters the family circle. Although Miles soon comes to like having him around and sees how happy his mother is, there are several things that bother him.
Eli comes and goes with no apparent pattern.
He talks about moving in so he can join what he calls their ''family romance'', but these, like so many other promises, remain unfulfilled.
And although he claims his divorced wife lives with their son on the other side of the country, Miles is sure he has seem him with a woman and young child in the neighbouring city.
At first he and his best friend Hector (who also occasionally interjects into the narrative) try to find out what is going on by themselves, but eventually they resort to hiring a private detective to check
Eli's background, and what they find out leaves them in a moral quandary. Is it better to let Miles' mother be happy even though it is an illusion, or tell her the truth and destroy the dreams she has been nursing for the past six years?
And what does it mean about the nature and possibility of love?
Casebook is both a sweetly sad coming-of-age story and an eloquent reminder of just how much our children piece together from those unguarded conversations and emotional tells we all have.
I am tempted to suggest this should be required reading for all parents.
• Cushla McKinney is a Dunedin scientist.
