The same technique of flashbacks is used to build the narrative history up to the point where there can be a climax to the story.
For that to happen Banks tells you what happened with Sophie and Alban in the intervening years after they were caught in a compromising situation in the garden. They meet in LA and make love, something she seems to regret, and then after that meet again years later at a trade fair in Singapore.
In Singapore he opens his heart and tells her that he loves her but she rejects him – details of that encounter to come – and he seeks refuge in drink.
At the same time there are episodes weaved in with his family, mainly his grandmother, who he hates for splitting him and Sophie up. She can read him like a book and realises he is unhappy and wants to leave the family firm.
You also suspect she is the one behind his mother’s suicide but maybe I’m shooting the gun there. Mind you there is a murder mystery element to this book as well as the love story that surrounds Alban - will it be Sophie or the mathematician.
The mathematician drives him up to Garbadale and makes a subtle but convincing pitch to stay with him. But all she can do is wait to see what happens when Sophie arrives.