For more than 20 years, one organisation has been chronicling in detail Stalin's mass terror. In Vladimir Putin's bling-charged autocratic Russia, that is no easy task. The offices of Memorial are regularly raided by so-called tax inspectors and other assorted thugs. But its groups of volunteer archivists and historians plug away in a society increasingly eager to "move on" and impervious to state-sponsored violence.

Russia's seeming inability to come to terms with its past, particularly the butchery of the Stalin era, is the theme of Stephen Cohen's commendable new book, The Victims Return. Cohen has visited and worked in the country from Brezhnev's time of "stagnation" to the present day. He came to know some of the offspring of the "zeks"  the millions taken away to labour camps, most of whom were either shot or died under the harsh conditions.

Thanks to Aleksandr Solzhenitsyn, Eugenia Ginzburg and others, the horrors finally became known to all. Cohen's book is not a history of the camps, but a history of the survivors and their legacy. Why was it that many surviving inmates subsequently joined the Communist party or tried to do so? "For some membership was mainly a way of obtaining a better apartment, job, pension and other state benefits," Cohen writes. "For others, it was an affirmation of complete exoneration."

The prospects for rehabilitation  even the barest sign of acceptance: the right to live in Moscow or Leningrad, for example  depended on each regime that followed Stalin. For a brief spring under Nikita Khrushchev, victims, or the sons and daughters of victims, found themselves accepted again, some even gaining high political office. The Soviet leader took huge political risks in repudiating his predecessor. In so doing, he was not only undermining the ideological underpinning of the state but challenging pretty much everyone in any position of authority. Cohen quotes Khrushchev as saying: "I have blood on my hands up to my elbows."

Once Khrushchev was seen off, Brezhnev rehabilitated Stalinism. Cohen quotes a senior Kremlin official of the time as instructing historians: "All  and I repeat all  stages in the development of our Soviet society must be regarded as positive."

It fell to Gorbachev to try to complete Khrushchev's work. In two years, he exonerated more than a million people. Cohen describes how important these letters were to families still craving acceptance half a century later. In 1988, the Memorial Society was established. Endorsed by Gorbachev, it sought to identify and commemorate the dead, but also to help the dwindling number of survivors. As once-closed cities were being opened, so information about the past came to light in newspapers and even on state-run television.

After 1991, and the formal demise of communist power, all remaining victims were rehabilitated. "The state that had raised, arrested and then liberated Stalin's victims ceased to exist," Cohen observes. In the chaotic but invigorating first years of Yeltsin, when the old rules were torn up, this thirst for historical accuracy continued. As Cohen points out, the economic theft that took place in the 90s led to a desire for order and the arrival of Vladimir Putin in 2000.

Yet Cohen's bizarre indulgence towards Putin, both in this book and in his jounalism, detracts from his authority when talking about dissent and human rights. Yes, Solzhenitsyn was given a quasi-state funeral. Yes, in a small number of highbrow papers with low circulations, a modicum of criticism is aired. But Putin's grappling with the past is not "contradictory", as Cohen asserts. It is worse than that. Russia is locked in historical denial  made smoother by sushi, Cartier and private jets  at least for some.

John Kampfner is the author of Blair's Wars and Freedom for Sale