In his extraordinary novel The White Hotel, D. M. Thomas introduced a succession of apparently disparate “documents”—an exchange of letters between analysts; the violently erotic imaginings of a young woman recorded in blank verse between the staves of Mozart's Don Giovanni; a prose journal written by the same woman; Sigmund Freud's (fictional) case study of “Anna G.”; a traditional, third-person narrative giving the history of Frau Elisabeth Erdman, a k a Anna G.; a chilling account of the Holocaust at Babi Yar, and a surreal scene in which the resurrected heroine meets her beloved dead.

As the novel progresses, the essential connection between these perplexing fragments becomes manifest; each is, in some sense, a translation of the last: Moving from poetry, the most subjective of literary forms and that closest to the dream language of the id, to an account that assumes the objectivity of history, D. M. Thomas explores the means through which literature attempts to come to terms with experience—with the complicated meeting of self and world. How, The White Hotel asks, do we arrive at meaning? How do we arrive at truth?

D. M. Thomas returns to the same questions, adopting similar literary methods, in “Russian Nights,” the quintet of novels written after The White Hotel, which Lying Together concludes. The sequence of novels, which began with Ararat in 1983, followed by Swallow (1984), Sphinx (1987) and Summit (1988), is unified (the author notes) by the theme of improvisation: “the mysterious way in which a word, an image, a dream, a story, calls up another, connected yet independent.”

“Russian Nights” is dedicated to Pushkin, who presides over the quintet much as Freud presided over The White Hotel, both as progenitor and character. Mr. Thomas's improvisational novels were inspired by a narrative fragment called “Egyptian Nights,” which Pushkin began in 1835, two years before he was killed in a duel. In the Pushkin story, a poet named Charsky, writing in his study, is interrupted by a foreigner whose shabby aura excites his suspicion. The stranger, it turns out, is an improvisatore—a performer who extemporizes verse on themes suggested by an audience—who has come to ask Charsky's help in acquiring patrons. Demonstrating his art, the improvisatore asks the Russian poet for a theme and the latter offers: “The poet himself should choose the subject of his songs; the crowd has no right to direct his inspiration.” Obliging, the foreigner begins with these lines: “Eyes open wide, the poet weaves / Blind as a bat, his urgent way.” Later on, at the evening Charsky organizes to introduce him into Petersburg society, the improvisatore begins a brilliant poem on the subject of “Cleopatra's Lovers.” In the middle of the verses, the story breaks off.

Mr. Thomas, who is one of Pushkin's foremost translators, inserted the entire text of “Egyptian Nights” into Ararat, the first novel of his quintet. He framed that story, however, in a dizzying spiral of authorship. At the beginning of the book, a Russian poet named Sergei Rozanov amuses himself by improvising a story—a talent he has inherited from his Armenian grandfather. His subject is improvisation. Rozanov imagines three other writers thrown together by chance at an international conference who agree to collaborate on an improvisation of their own. They create a character named Victor Surkov, a repulsively trendy Russian poet who in his turn invents alternative endings for Pushkin's unfinished story, one of which imitates Pushkin's own real ending—a duel over his wife's honor. At one point in the narrative, Surkov seems to become Pushkin.

Swallow, Sphinx and Summit gave variations on the theme of improvisation, introducing many of the same characters and interlarding dreams, narrative, poems, a play called “Isadora's Scarf,” political satire, borrowed texts (H. Rider Haggard's King Solomon's Mines, for example) and historical events and persons. But Pushkin and “Egyptian Nights,” in one guise or another, were never far from sight. What interests Mr. Thomas in the story, from the evidence of the novels, is the paradox on which it turns: the improvisatore stands for creativity in its most elemental form (inspiration), but at the same time the subject of his verses is always something given to him. Literature, Mr. Thomas suggests, is a collaboration of past and present, repetition and invention, the world as given and the world imagined.

Lying Together seems at first to take a new tack. The “real” people behind the earlier fictions are unveiled: the narrator is Don Thomas, a British writer attending an international writers' conference in London. Here, he meets his Russian friends Sergei Rozanov, Victor Surkov and Masha Barash—all fictional characters in the earlier novels. The four writers discuss the novels they have improvised together—Ararat, Swallow, Sphinx and Summit—and agree to collaborate on a new one, Lying Together. The first four novels have been published as the work of “D. M. Thomas,” we learn, because Soviet censorship made it impossible to tell the truth. Now that perestroika has arrived, however, the Russians are agitating to have their part in the novels revealed, but Don Thomas tells them that the contract with Viking Penguin forbids it.

Subsequent twists of the plot reveal still more “real” people lurking behind fictional characters—as well as fictional characters who become real people, arousing the resentment of their inventors. Each mystery solved though, seems to create several more perplexities. And all the while, the character-authors are deceiving one another, interpreting one another, and giving the reader advice on how to read the books they've improvised. Victor Surkov, discussing Lying Together in an interview, remarks: “There's a sexual pun there, of course: in sex there's the same combination of lies and deeper truth.”

On the most intimate level, Lying Together insists that self-revelation is ultimately yet another form of fiction. We invent ourselves, then come to believe our own improvisations. But Mr. Thomas also intends his unfolding truths to function as a political metaphor, just as hysteria did in The White Hotel. Since Pushkin's time, improvisation—read disguise—has been the key to surviving the censors of both czars and revolutionaries. Where official language predominates, truth is no longer discernable.

An author's note prefacing Summit suggests D. M. Thomas intended that novel to conclude what he then called “The Russian Quartet.” Lying Together, I suspect, was written as a response to the subsequent events of glasnost and perestroika. Discussing Soviet President Mikhail S. Gorbachev's speeches with his Russian friends, the fictional Don Thomas remarks that “he seemed to strike a humanistic, philosophical tone quite different from the traditional dreary, shrill propaganda jargon; a tone, moreover, to which our politicians were incapable of responding. That was because truth, in the West, had become slowly corrupted, Surkov said; whereas in the Soviet Union it had had to go underground for seventy years. Therefore when it was tapped it was still pure, like a spring.”

Later on, though, Surkov tells a reporter from a London newspaper that “there is little actual censorship now, but there's something even more dangerous, in a way—self-censorship. Gorbachev is saying, Look, you guys, I'm trusting you; don't let me down! So we try not to let him down by censoring our works in our minds, or even our subconscious.”

Like The White Hotel, the “Russian Nights” quintet is an engaging literary performance: a learned, witty, intricately constructed inquiry into the tricky relationship between art and life. Yet somehow it lacks the power of the earlier novel. In the end the quintet is more interesting to discuss than to read. This may be because, for all the fragmentation of the narrative in The White Hotel, that novel is still compellingly held together by a story—a story whose heroine we come to care about. This is only episodically the case with the characters in “Russian Nights”; for the most part they lack dimension. What we are left with finally is theory. Novels require something more.