USA, California, 1993: Neil Collins and Adam Tayler, two young British men on the cusp of adulthood, meet at a hostel in San Diego. They strike up a friendship that, while platonic, feels as intoxicating as a romance; they travel up the coast together, harmlessly competitive, innocently collusive, wrapped up in each other. On a camping trip to Yosemite, they lead each other to behave in ways that, years later, they will desperately regret. The story of a friendship built on a shared guilt and a secret betrayal, The Faithful Couple follows Neil and Adam across two decades, through girlfriends and wives, success and failure, children and bereavements, as power and remorse ebb between them. Their bifurcating fates offer an oblique portrait of London in the boom-to-bust era of the nineties and noughties, with its instant fortunes and thwarted idealism. California binds them together, until - when the full truth of what happened emerges, bringing recriminations and revenge - it threatens to drive them apart.