"Confession With Blue Horses" by Sophie Hardach

It has a prologue (which I think isn't needed) - in 1987 a family tries to go over a border.

Then we're in London 2010. Ella, artist and office-cleaner, lives in an abandoned fishing boat on the Thames. Her bother Toby is a gay, well-off garden designer. When some items are forwarded from their year-dead mother's loft, they realise that she'd got further than they thought with investigating their sibling Heika's disappearance. Heika was 2 when they all tried to leave the DDR via Hungary.

Ella goes to Berlin to follow up the clues. We learn that her parents were art historians, that they befriended Sven, an artist, who fled to the West. She visits the Stasi archives where they're reassembling shredded documents, and befriends a male intern, Aaron, a Londoner. He finds files. "The Elephants" are the ex-stasi people who still work there. She visits a museum which was the prison where her mother was kept. She looks at the house where she was brought up, and looks for the house in the country where Sven lived.

We learn more about their attempted escape - the father was killed, the mother arrested. Two children returned to their grandmother. Who betrayed them? Sven? The grandmother? Evidently it was Ella who alerted the authorities, taking western toys to school and speaking carelessly. The mother's freedom was bought by the west. The wall came down and the family was re-united.

Ella tracks down a prison guard then her mother's interogator, who's been expecting her. He's unapologetic. He claims that Ella's mother visited him, that together they observed Heika, who looked happy (happier than her other children, she said), so she didn't introduce herself.

At Aaron's good-bye do his colleagues discuss their next project - about artists and the Stasi. Aaron suggests it should be entitled "Confession With Blue Horses" - Ella had told him that her mother had said that the 3 blue riders in the painting of the same name were the 3 siblings.

Ella tracks Heika down. He's living in the building where they were brought up. They meet.

I think we learn too much about the workings of the researchers into the Stasi doc, and of Aaron.

Other reviews

• Clare Clark
• themonthlybooking (I found the present-day scenes, set in 2010, utterly incapable of holding their own against the scenes of the late 1980s ... modern-day Berlin seemed like a caricature of itself, far too full of hipsters and off-the-wall nightlife to be a convincing place. Yes, Berlin is famed for these things, but this too stereotypical portrayal seemed jarring in comparison with the meticulous authenticity of Hardach’s 1980s version and I often found myself disengaging. ... I couldn’t help but feeling that it is maybe too flimsy a vehicle for some of the bigger themes it touches on.)
• goodreads