Which C.S. Lewis book contains the allegorical character George MacDonald as a guide?

The Great Divorce contains the allegorical character George MacDonald as a guide.

Published in 1945, The Great Divorce is a short theological fantasy about a bus journey from a grey, shadowy version of Hell to the outskirts of Heaven. The unnamed narrator meets figures who represent different spiritual and moral choices. George MacDonald, a nineteenth-century Scottish author and Christian thinker admired by Lewis, appears as a guide and interpreter.

The book’s title alludes to William Blake’s The Marriage of Heaven and Hell, but Lewis reverses Blake’s emphasis. Lewis presents separation rather than union as the central image, exploring freedom, repentance, self-deception, and the consequences of refusing joy.

George MacDonald was a major influence on Lewis’s imagination and religious thought. Readers sometimes confuse this book with The Pilgrim’s Regress, another allegorical work by Lewis, but The Great Divorce is the one that specifically features MacDonald as the narrator’s guide.