This terrific book, which had me gripped from the start and which I buzzed through in a few happy hours, is about the land speed record - in other words, about men and vehicles. The vehicles are strange and scary - huge, ugly constructions, engine-heavy, uncomfortable, terrifically dangerous. If anything, though, the men are even stranger and scarier. They are obsessive, compulsive, deeply flawed, with self-destructive tendencies. There is a lot of untimely death in this book, as well as sharp historical detail.

Even though the land speed record (or LSR) was first set in 1898, by Gaston de Chasseloup-Laubat, and broken as recently as 1997 by Andy Green, Jennings concentrates on the inter-war period - the LSR's golden age. I had never heard of either Chasseloup-Laubat or Green. In 1898, when the LSR was 39mph, it was not big news, just as it is not big news today that the record is 766mph. These days, as the author notes, all you see when you watch a record attempt is "plumes of smoke in the distance".

Jennings sets the scene well. He tells us that, after the First World War, there was a palpable feeling in Britain of national decline. "At most measurable points," he writes, "Britain was diminishing." The armed forces were being cut back. Trade was down. The LSR, he says, was "a kind of non-violent colonialism" - something to restore British pride. And when, in 1927, John Parry Thomas - a Welsh engineer with bad teeth - crashed his car at 180mph in an attempt to break the record, decapitating himself in the process, the doctor who oversaw the inquest at his death said: "These attempts by brave men only show that in 1927 the manhood of the British empire is not dead."

The book really takes off when Jennings introduces the men he calls the speed kings: Henry Segrave, Malcolm Campbell and John Cobb. They were the David Beckhams, or at least the Ayrton Sennas, of their day. Segrave, an Old Etonian who had first been wounded in the trenches, and then again as a pilot, took part in the first ever British Grand Prix. His car broke down. Then he saw the potential of the LSR - an arena with "an aura", as Jennings puts it, and which, "like all great sporting endeavours", was "easy to grasp". Segrave built himself a monstrous machine that he called "the Slug", which was "the length of a suburban sitting room", shipped it to Daytona Beach, Florida in 1927, and clocked a record time of 203.7mph.

While Segrave was an outwardly calm man who built model railways, his great rival, Malcolm Campbell, was quite the opposite. Campbell, another ex-public schoolboy, was constantly flirting with disaster. He was mean and manipulative, a desperately insecure man who had been thrashed a lot at school and whose father had never valued him. Campbell built his own monstrous vehicle, which he named Blue Bird. In 1928, he took the record from Segrave by 3mph. In 1929, Segrave took it back with a speed of 231mph. In 1931, Campbell struck again: 246mph. Eventually, Campbell topped 300mph, only to be pipped by another Old Etonian, John Cobb, who managed just under 370mph in 1939.

What made these men tick? This is one of the fascinating questions raised by the book. They all had bad childhoods, for one thing. Segrave's mother died when he was a child; later, he was disabled by his wounds. Campbell had his thrashings to deal with. Cobb had been bedridden with tuberculosis, and it was assumed he would die. These three men somehow expres- sed the national zeitgeist. Outwardly privileged, they had been diminished by life. They craved greatness and self-destruction, possibly in equal measure.

Fascinatingly, both Segrave and Cobb came out of retirement to make attempts on the water speed record. Segrave broke the record, which was 100mph, in June 1930, but his boat jinked oddly flinging him into the water. He died of haemorrhages in the lungs. His last words were, "Did we do it?" Twenty-two years later, Cobb attempted the same feat. By now, the record was 179mph. Cobb got up to 240mph, but fell foul of uneven water. His boat was ripped apart, and that was the end of him.

The Fast Set is a lovely read, full of excitement, but there is a great deal of very British unspoken pain here, too. Jennings has captured the essential characteristic of these men - their sadness - extremely well.