The Sandcastle by Iris Murdoch is, at its heart, a love story. However, the love story is a bit convoluted because the main character, Bill Mor, is already married. Mor is a man fast approaching middle age, and his life in the novel focuses on the romantic spark that results from the arrival of a young woman named Rain Carter. The story shows us a man who is deeply dissatisfied with life; Mor was passed over for a promotion, hates his new boss, wants to become a politician, and feels trapped by his overbearing wife.

Despite the novel being published in 1957, the tone is sympathetic to Mor’s infidelity. He is treated like a sympathetic character who falls into adultery, being acted on rather than the actor. Murdoch shows us early on in the novel why Mor is susceptible to an affair with Carter. The first scene of the novel opens with Nan berating Mor for the cost of the portrait. She comes off as a stingy nag, using phrases like:

“You could articulate more distinctly,” said Nan, “if you took that rather damp-looking cigarette out of your mouth.”

And

If you ask me, it’s you and the school Governors that are mad.

The opening argument between Nan and Bill shows the state of their relationship—how he feels trapped and hampered by his wife, who doesn’t support any of his decisions or ambitions. Bill harbors ambitions to run for political office, but that is something his wife is entirely against. Their entire relationship is painted negatively at the start of the novel, which sows the seeds of a new love to be planted when he meets Rain Carter.

Bill works at the school where the painting was commissioned, and he meets Carter at a party thrown by the outgoing headmaster, Demoyte. When he meets Carter, Mor offers to take her around the city and show her the sights.

Despite a terrible outing wherein Mor damages her car, Carter and Mor slowly fall in love. Their affair never culminates in sex, but it is eventually discovered by his wife when she returns early from a trip she took with their daughter. Mor, who is stuck, can’t decide what he wants in life. That issue—Mor’s inability to act in his interests—is the crux of much of his dismay in the story.

In the end, everything comes down to Rain Carter’s decisions. At the reveal ceremony for the painting, Nan comes out and supports her husband’s political ambitions publicly, a move that pushes Carter to realize that their relationship is not something she can pursue. She finishes the painting and goes back to France.

The story of Bill Mor’s romantic infidelity is unusual in the way that it never really comes down to Bill’s decision. Bill is incapable of making a decision, and for most of the book, he is trying to follow his heart, but he can’t make the leap to go with Carter—despite falling in love with her.

Their love story is typical of affairs in that Bill feels lonely and stifled in his married life, and Carter, a much younger woman, offers him a taste of a new life. That new life, though, cannot come without a cost, and that is ultimately what leads to its end. Carter is not willing to sacrifice Bill’s marriage for the fulfillment of her love.