Say you’re friends with a writer. Say one day your writer friend asks you to lunch. You ask what’s going on. She tells you, “I’m working on a book.” A book, you reply, that’s great! What’s it about?

“Well, here’s the thing,” she says. “I’m writing a sequel to The Wind in the Willows.”

Here’s where you’d gently try to convince your friend that she’s making a horrendous mistake, that the world doesn’t need a sequel to Kenneth Grahame’s beloved children’s classic. And just about any time, you’d be doing your writer friend a favor. But if your friend is Kij Johnson, you should just nod, tell her you look forward to reading it, and enjoy the rest of your lunch.

Johnson is one of the most important sci-fi writers in America today — one of the few names mentioned as a natural successor to Ursula K. Le Guin and a true standard-bearer of fantasy fiction. Her latest book, The River Bank expands on and explores the themes of Grahame’s novel with all the dignity and resourcefulness that the subject matter demands. (Johnson reads from The River Bank this Tuesday at Elliott Bay Book Company.)

As you’d expect from Johnson, River provides a feminist spin on Willows. The opening line identifies the most important change Johnson makes to Grahame’s mythos:

The news was everywhere on the River Bank and had been heard as far as the Wild Wood: Sunflower Cottage just above the weir had been taken by two female animals, and it was being set up for quite an extended stay.

It’s a divisive move:

The satisfaction felt by the feminine residents of the River Bank was not, alas, universal. A few days after the arrival of Beryl and the Rabbit, the Mole said to his friend, the Water Rat, “I do not see what all this fuss is about. We were going along very well without these two setting everything at sixes and sevens.”

Even the Rat, a confirmed bachelor, felt this was unjust. “Now, Mole, that’s not fair; you know it’s not. There was a lot of here-ing and there-ing at first, but now things are nearly as they were The young ladies keep to themselves. Why, we hardly see them!”

It’s like Twitter, with talking animals.

Fans of Willows will find much to appreciate here. Johnson appreciates the traditions — she writes a great, rampaging Toad — even as she builds on them. The animals of the River Bank, Weasel and Rabbit and Rat, all wrestle with big questions of change and tradition, and community. There’s a ransom plot, and a decent coshing. It’s all in good fun.

Johnson makes a bold inquiry into Willows’s class distinctions — it’s a story of upper-class men in a pristine rural land — and in so doing matures and expands the characters. She’s not burning down Grahame’s world, she’s engaging it in a deep and meaningful conversation, taking the characters by the hand and slowly introducing them to the modern day.

But even as she interacts with the world of Willows, Johnson never forgets to pay homage to Grahame’s gorgeous prose style — that deceptively lyrical language that lures children in and then grows and deepens with them as they age. Johnson is not intruding on alien land, here — she’s doing Grahame a boon by building on what came before.

Elliott Bay Book Company, 1521 10th Ave, 624-6600, http://elliottbaybook.com, 7 pm, free.