At the close of this novel Lilly Bere, an 89-year-old Irish-American, sits alone in her little house on Long Island after the suicide of her soldier grandson, Bill. He has come back, traumatised, from the first Gulf War. Lilly thinks back to a Dublin childhood. Her family then - two sisters, brother and policeman father - feel closer than the growling storms of the Hamptons shore outside. “There is never a day goes by that we don’t drink a strange cup of tea together, in some peculiar parlour-room at the back of my mind.”

In both drama and fiction, Sebastian Barry has often refreshed himself from that ever-brewing pot. His admired play The Steward of Christendom drew for the character of Thomas Dunne on the life and fractured times of Barry’s grandfather, chief superintendent of the Dublin Metropolitan Police and faithful servant of the British crown as Ireland rebelled. The novels Annie Dunne and A Long Long Way took as their protagonists two of the Dunne children: the lonely Annie and Willie, a soldier of the Great War wrenched apart by divided loyalties.

On Canaan’s Side, Barry’s first novel since the Costa Award-winning The Secret Scripture and already long-listed for the Man Booker, once more revisits the Dunnes. It follows Lilly’s bruising odyssey as she flees to America after the collapse of the imperial Ireland that her father loved. There, “on Canaan’s side”, in “the place of refuge itself”, she encounters not simple peace and plenty but a battle for life through murder, poverty and successive wars.

In a way, Lilly prevails. She endures loss after loss to nest here on a swanky coast, the beloved former cook of a family related (as we slowly learn) to the Kennedys. “A grateful relic, for what I was given, if not for what was taken away,” she nonetheless inspects her deep wounds in a journal written after Bill’s death. And she concludes that “the pressure of sorrow is like being sent down to the core of the earth. So how are we not burned away?”

Barry’s writing suggests that memories rehearsed in a language that out-sings tragedy will, if not fireproof us, at least retard the flame of grief. Anyone who knows his work will seek, and find, a lyrical incandscence in Lilly’s narration. At its mid-point a single two-page sentence moves with her up and down a roller-coaster in Depression-era Cleveland and, via its own spectacular swoops and lurches, captures in miniature Lilly’s, and America’s, “long story of suffering and glory”.

In haste, she - the fearful daughter of a despised loyalist, “a useless name with a useless story” - has slipped out of revolutionary Ireland with her sweetheart, Tadg Bere. A former soldier, he has tumbled into the hated militia, the Black-and-Tans. Tadg now has a price on his head and - in Chicago’s art institute, in front of a Van Gogh self-portrait - his republican pursuers will collect it. On the run again, Lilly fetches up as a maid in Cleveland in love with the enigmatic cop Joe: defender of her black best friend, Cassie, but a man bearing a secret “weight”.

Joe forsakes Lilly, for reasons that gradually emerge. Further revelations, more at a gallop now, accompany her post-war security as household treasure to an elite clan. As her son Ed drifts away - injured invisibly by one of this novel’s endless wars, in Vietnam - Lilly fears that “I had contaminated him”, and that “the poison ... in me, was history”. That toxin, drip-fed through the first half, gushes in the second. Her memories, lavishly drawn out over the flagstones of Dublin Castle (where her father served) or the heather-strewn hillsides of Wicklow, concertina now. Sudden flares of love and pain punctuate the fast-flowing decades.

That’s how long-distance reminiscence works, perhaps. Yet this shifting rhythm unbalances the book. Barry’s core theme, with the loyalist family bereft as “all the world [her father] knew had gone on fire”, lends the early sections a scorching passion. In rackety Chicago and Cleveland, as “the generous American sky threw all its arms open”, Lilly’s gaze as a hyper-attentive fugitive brings freshness to the familiar migrant record. Sinister images of fire and flame recur. Yet too much then rattles by too fast: great sorrow, little room. We end with the posh, blowy Hamptons a ghostly grey outside, and Dublin Castle before the 1916 deluge intensely present as a dark harbinger of future tumult - Yeats’s “rough beast”, maybe - surges from its shadows.