In Chang-rae Lee's debut novel, "Native Speaker" (1995), a Korean-American industrial spy undergoes an identity crisis when he is tasked with shadowing a Korean-American politician. Lee's second novel, "A Gesture Life" (1999), returned to the plight of the isolated immigrant, with Lee sharpening his focus on the twin trials of assimilation and alienation. In his latest and boldest novel, "On Such a Full Sea," Lee's characters are Chinese immigrant workers in the United States — specifically Chinese workers from a long-elapsed China toiling in a fast-declining America a century or so from now. For Lee's heroine, Fan, the issue is not acclimatization but self-discovery. The adventures of this feisty yet wary protagonist, together with a bleak but arresting vision of the future, keep the reader rapt and concerned for the fate of both beleaguered character and battered brave new world.

Lee opens with a snapshot of fish-tank diver Fan and B-Mor ("once known as Baltimore"), a settlement now comprising forced labor colonies. Whole communities work six-day weeks, cultivating produce for their wealthier neighbors in Charter villages. However, Fan is disillusioned and heartsick. One day she shocks the colony by up and leaving in search of boyfriend Reg, who has vanished. B-Mor's incarcerating walls give way to scarred landscape, hostile plains and lawless states. Fan's aimless journeying brings her in contact with ragbag characters and frequent jeopardy, so that in time her cocooned existence is a distant memory. Only her wits, her resolve and the sporadic kindness of strangers can keep her on course and steer her toward her lost love and greater understanding.

Some readers may have thought Lee had peaked with "The Surrendered" (2010), his superb, daring, multifaceted study of the Korean War and its fallout. "On Such a Full Sea" lacks its predecessor's epic sweep, but it matches it in scope and surpasses it in inventiveness. Lee's futuristic America is redolent of the post-apocalyptic worlds of J.G. Ballard: not science fiction, more the speculative fiction that Margaret Atwood occasionally dabbles in. As such, we are presented with a harsh but believable dystopia, a glimpse of what could happen. "Imagination might not be limitless," we are told. "It's still tethered to the universe of what we know." Outside "our clement realm," Lee's reality-hit characters weather a catastrophic economic decline and risk contracting fatal C-illnesses or violent attacks in The Smokes.

Lee's novel is essentially a road trip, with drama and perversity punctuating the route like milestones. Fan is drugged and kidnapped by the mysterious and tragic Quig, set upon by a psychotic acrobatic troupe, and taken under the wing (and into the boudoir) of Miss Cathy and her seven nameless girls. We are routinely disoriented and yet reluctant to deviate from Lee's storytelling. Certain passages may be too thick with finicky detail on, of all things, fishery operations, but they are quickly followed by the next exciting or moving stage of Fan's quest and, buried within, subtle commentary on such binaries as illness and survival, love and friendship, community and individuality.

There is a final surprise in store at Fan's journey's end, but it polishes what already shines. In Lee's richly imagined and skillfully executed work, the joy of traveling far outpaces the satisfaction in arriving.

Malcolm Forbes has written for the Times Literary Supplement, the Economist and the Daily Beast. Born in Edinburgh, he lives in Berlin.