Every so often a book comes along that does more than stop you in its tracks. It yanks you in, envelops you, makes the rest of the world dim and cloudy. While in thrall to such a book, everything outside its covers is unimportant. Housework, homework, any other kind of work goes to the wayside. Family and friends will be baffled, possibly irritated, hopefully understanding. And after the book is done, you wander about for a week in a cloud of irritation, expelled from the world that held you so completely.

Edith Pargeter’s The Heaven Tree is such a book. It involves a terrible blood bond between three people in the Middle Ages, a bond that descends through years and generations, and revolves around the building of a great cathedral. Do not say a word about Ken Follett’s Pillars of Earth. This is the best book about cathedral-building ever written, and many other things as well: a character study, a drama, a romance, and a ripping good yarn.

It begins simply enough with Harry Talvace, a cheerful young English lordling who gives up his birthright to follow his passion, which is carving stone. His dream is to build a great cathedral, and he at last gets the chance when he meets Ralf Isambard, a powerful and enigmatic marcher lord from the border of Wales who hires Harry as his cathedral architect. Joining this band are various other characters: Benedetta, Isambard’s beautiful and serene Italian mistress; Gilleis, Harry’s fiery little wife; and Adam, Harry’s best friend and chief stonemason. The cathedral begins to rise.

So far, so good–a bustling story of the Middle Ages, with a few fascinating sidebars into Welsh-English politics and the technical aspects of stone-carving. The book’s genius is in the slow-building dread of its plot, for Harry has made a rash promise to Isambard, and events will force him to break it. No one breaks promises to the terrible and inexorable Isambard, and Harry’s life is forfeit. No one can save him, not even Benedetta who has come to love Harry–but she can foil the execution. The scene that follows is nearly unbearable, as the life and soul of a good man are stretched between the woman who loves him and the lord who loves him too but loves vengeance more.

The Heaven Tree is technically a trilogy, though it reads as almost one book. The next continues a generation later with Harry’s son, now a young man and thirsting to avenge his father’s death. His attempt fails, and he becomes Isambard’s prisoner. A game of cat and mouse ensues as young Harry tries to remain firm against the old lord’s wiles–and find out what it is Isambard wants from him, and from Benedetta who is now living a hermit’s life in the Welsh mountains. Over everything looms the cathedral his father made, a miracle in stone that may hold redemption even for Isambard.

There are passages of extraordinary lyrical beauty. The weeks when the first Harry, knowing his death is imminent, pours his frustration and fear and will to live into his stone-carving, filling his nearly-finished cathedral with all his angel’s soul. The time when Benedetta flings the gauntlet down before Isambard. The scene by the river, nearly impossible to read. An incidental passage where a crusty old saint quietly dies in the grass outside his hut. And the final chapters where Isambard and Benedetta, in the cathedral Harry built, come to terms with everything they are and everything that has gone before them.

This is a long book, and it is slow to begin. Do not make the mistake of abandoning it after forty pages in frustration. Stick with it until Isambard and Benedetta join Harry, and their fateful triangle is in place. The Japanese have a term called en, which refers to a karmic connection between people which draws them inexorably together throughout their lives. The en between Harry, Benedetta, and Isambard is a thing of beauty and terror, blood and genius.

This book is not well known. It should be. It is a work of unbelievable power.