The Secret Speech, By Tom Rob Smith

Tom Rob Smith's extraordinary debut novel, Child 44, was longlisted for the Man Booker Prize (unusual for a thriller) and won a Crime Writers' Association Dagger. In that book, Leo Demidov, a fanatical Stalinist agent, falls foul of his masters, recants and turns outlaw, all the while attempting to solve scores of scattered child murders in a state where such decadent crimes are deemed officially not to exist. In this follow-up, Leo and his wife Raisa have adopted the two country girls, Elena and Zoya, whose parents were slaughtered by Leo in the first book. Leo's continuing salvation, we understand, depends on the girls' happiness and well-being, though Zoya, the eldest, hates him, standing over his sleeping form at night with a kitchen knife.

Smith's strength is the way he underpins frankly melodramatic plots with riveting historical detail. The first book's serial killer turned out to be less terrifying and infinitely more pathetic than the high-ranking Soviets who gleefully sent their fellow citizens to be tortured and killed. In this book, Stalin is dead, and the "secret speech" of the title is a measured acknowledgement of the former leader's crimes and errors. But Khrushchev's apologia has prompted violent uprisings in the countries under Russian rule, while in Moscow the criminal underworld, sensing weakness, is on the rise. Those now in control of the Soviet Union will stop at nothing to stamp out the freedom movement.

Of more immediate concern to Leo, now running a not-quite-official homicide unit in Moscow, is the fact that somebody is trying to assassinate former agents. In the opening flashback pages we see the 24-year-old Leo in the bad old days; adopting the name Maxim, pretending to be a theological student, he infiltrated an Orthodox Christian group and sent its leader to the Gulag. When the patriarch who connived at the persecution of priests is assassinated, it seems the dangerous unrest in Moscow is somehow linked to Leo's past. What follows piles the Pelion of non-stop breathless action upon the Ossa of psychological implausibility. We follow Leo into the Moscow sewers in pursuit of a vory gang, on board a ship to the Gulag, through the icy wastes of Siberia and on to Hungary in the throes of an uprising. Unholy alliances form between tattooed gangsters and Soviet paymasters, further complicating an already tangled story.

Leo and Raisa have become measurably flattened as characters, reduced to a series of impulses: but-I-love-him; not-without-my-child; I-will-have-my-revenge. Zoya is a strange creation. "Perpetual unhappiness seemed vitally important to her," Smith observes, but her psychopathic ill will starts to look like he just can't be bothered to do anything with her beyond making her drive the plot.

Who cares, though? Tom Rob Smith has created another insanely exciting story, while making you feel you're learning a bit of history along the way. The really horrible scenes here are the ones he hasn't made up. No matter how perfunctory the characterisation or writing, you can almost smell the sewers, hear the rumble of tanks, feel the frostbite. But I hope Leo and Raisa get their personalities back in time for the next outing.