An unfinished book by J.R.R. Tolkien that was completed by his son will be published April 17 in Canada, New Zealand, the U.S. and the U.K.

Christopher Tolkien, son of the man who wrote the Lord of the Rings trilogy, has completed The Children of Hurin, a book his father started in 1918 and later abandoned.

J.R.R. Tolkien, shown in a 1967 photo, left notes and an outline for The Children of Hurin, a novel finished by his son and to be published in April.
(Associated Press)

Publisher HarperCollins is not releasing details of the book, but describes it as "an epic story of adventure, tragedy, fellowship and heroism."

The younger Tolkien previously drafted The Silmarillion and History of Middle Earth from drafts of his father's work.

The Children of Hurin will be illustrated by artist Alan Lee, who won an Oscar for art direction on Peter Jackson's film The Return of the King.

Lee has provided 25 pencil sketches and eight paintings for the book.

Parts of the text of The Children of Hurin, which takes place in Middle Earth before the events of Lord of the Rings, have appeared in History of Middle Earth.

Tolkien said he has worked on the book for 30 years based on unfinished pieces and outlines done by his father.

The Lord of the Rings trilogy has sold more than 50 million copies worldwide.