Canada - 'The true north strong and free' in the words of its national anthem - is the subject of this exhilarating new travel book from Paul Theroux: both a journey into the past and a cross-country road trip in the present, at a pivotal point in Canada's history.

A vastly diverse and geographically scattered nation of forty million people, Canada is now threatened with annexation as the 51st state by the US President, beyond the longest undefended border in the world. This threat has had the effect of unifying the nation, inspiring patriotism, and encouraging the normally laconic Canadians to be forthcoming, ideal for a traveller with a gift for listening.

For Theroux, this journey is also personal: his ancestor Antoine Theroux left Gascony in 1693 to become a pioneer in Nouvelle France and to settle in the small village of Yamaska, where many Therouxs still live and thrive. He recounts the riveting story of Antoine, illuminating the deeper, and often darker, history of Canada, before hitting the road from Yamaska, to explore the length and breadth of the country.

From the farthest east in Newfoundland to the west in Vancouver, Theroux travels the highways linking Quebec, Montreal, Toronto and the huge cities of the prairies - an archipelago of urban islands, surrounded by vast, often pristine landscapes. Along the way he meets farmers and fishermen, writers and activists, new immigrants and old timers - each a vital part of this True North, each hoping for it to remain strong and free.

With his remarkable gift for description and narrative, and his zest for the open road, Paul Theroux remains the most compelling, searching and evocative of travel writers.