Kingsolver, at the top of her craft, builds pyramids of language and scenic highways through mountains of facts, while plotting a mostly tight course through the fictional premises that convey her writing’s social conscience. In this book, pacifism, social justice, and free expression are the standards she shoulders.

“The Lacuna” can be enjoyed sheerly for the music of its passages on nature, archaeology, food and friendship; or for its portraits of real and invented people; or for its harmonious choir of voices. But the fuller value of Kingsolver’s novel lies in its call to conscience and connection.

Barbara Kingsolver's new novel, "The Lacuna," is the most mature and ambitious one she's written during her celebrated 20-year career, but it's also her most demanding. Spanning three decades, the story comes to us as a collection of diary entries and memoir, punctuated by archivist's notes, newspaper articles, letters, book reviews and congressional transcripts involving some of the 20th century's most radical figures. The sweetness that leavened "The Bean Trees" and "Animal Dreams" has been burned away, and the lurid melodrama that enlivened "The Poisonwood Bible" has been replaced by the cool realism of a narrator who feels permanently alienated from the world.

A serious problem with The Lacuna is telegraphed in its striking title. "Lacuna" refers to a gap or something that's absent. The motif of the crucial missing piece runs throughout the novel, but the thing unintentionally missing here is an engaging main character. Our hero, Harrison Shepherd, is an accidental onlooker to history buffeted by other people's plans and passions.

Narrated in the form of letters, diary entries and newspaper clippings, the novel takes a while to get going, but once it does, it achieves a rare dramatic power that reaches its emotional peak when Harrison wittily and eloquently defends himself before the House Un-American Activities Committee (on the panel is a young Dick Nixon). Employed by the American imagination, is how one character describes Harrison, a term that could apply equally to Kingsolver as she masterfully resurrects a dark period in American history with the assured hand of a true literary artist.