London Under, By Peter Ackroyd

Ackroyd's London: The Biography (now available in a concise edition from Vintage) is the non-fiction masterpiece of this prodigiously productive author. Packed with startling detail, its thematic approach ran rings round conventional chronologies of the city. From the chapter on London's distinctive smells, we learn that "Long Acre smelled of onions and Southampton Row of antiseptic". A companion volume Thames: Sacred River was a disappointment – too much obscure history, not enough humanity. The magic has returned with Ackroyd's curiously named subterranean coda to London: A Biography. Anyone intrigued by this tumultuous city will devour London Under in a few transporting hours.

Ackroyd's view of this "sequestered and forbidden zone" does little for London in PR terms. His discussion of the Tube presents a contrary view to the cheery documentary series currently showing on BBC: "A general air of depression seeps through the walls of the Underground." A chapter on sewers notes that, prior to the massive Victorian constructions, "It might seem that London was sitting on a lake of shit."

London Under is packed with revelations. Ackroyd elucidates the curious contortions of Marylebone Lane: "the twists and turns... accurately plot the course" of the now forgotten Tyburn River. A chapter on Forgotten Streams also reveals that the Westbourne passes through "a great iron pipe" at Sloane Square Tube station, while the Effra, a waterway once negotiated by Canute, explains such perplexing Brixton names as Coldharbour Lane and Rush Common. A more recent mystery is "a small steel trap-door" in Leicester Square that is "disguised to baffle or prevent unwanted visitors". It is the portal to a "vast electricity station" that descends over three storeys.

Brooding oppression is a recurrent theme. It crops up in chapters on underground pipes , tunnels under the Thames and the use of Underground stations as refuges during the Blitz ("No heroism, or bravery, manifested itself; only misery and squalor"). The book ends with the less than cheering thought that "the underworld... repels clarity and thought. It may offer safety for some, but it does not offer solace. London is built on darkness." Ackroyd's stylistic brilliance explains why the book remains a rattling good read despite its pervasive psycho-geographical angst.