The most any of us probably learned about the arcane discipline of alchemy is that it had something to do with turning base metals into gold. What far fewer of us may realize is how much the fanciful and seemingly impossible principles of alchemy contributed to the hard sciences of today, such as physics and chemistry.

In THE ALCHEMIST'S DAUGHTER, British novelist Katharine McMahon has stepped boldly into that shadowy period during the early 1700s when alchemy was in its twilight and the new physical sciences --- identified by such luminaries as Sir Isaac Newton --- were emerging into daylight.

For those at the top of the great societal heap known in Britain and Europe as the Age of Enlightenment, the whole universe must have seemed ripe for the picking. Scientific discoveries had vastly improved navigation, trade, medicine and manufacturing, bringing exciting new products, pastimes and services into the lives of those able to afford them.

Living outside London in a rundown rural estate on the periphery of all this activity, Emilie Selden, an unlikely apprentice to her reclusive widowed father, grows up as a rigorously trained natural scientist and philosopher. Barely aware of social graces, human emotions or the domestic arts, Emilie spends most of her first 19 years immersed in the intellectual crucible of her father's laboratory.

Then the opposite sex happens. Now that would seem almost a basic necessity for a historical novel, except that at this point several things could happen. The story could have dissolved into a banal romance with the usual steamy vocabulary; it could have forged virtuously onward as a boring triumph of feminist brains over shallow amour; or it could have lost its way entirely and become a social justice tract about how hard life could be for the working classes.

But this is where THE ALCHEMIST'S DAUGHTER shows much more than its scholarly mettle. From this most delicate turning point --- the year 1725 "when everything changed" in Emilie's retrospective eye --- McMahon achieves a brilliant, poignant and utterly unforgettable tour de force that weaves together the real complexity of human confusion and aspiration.

It's not only about a brilliant young woman surviving on the edge of her social and historical milieu; it's not only about love betrayed and love fiercely guarded; and it's not only about the thundering clash of ignorance and ethics. In McMahon's supple and experienced hands, her story is all of this and much more. Emilie is so fully and powerfully drawn that she fills, overflows, the strangely diverse historical container in which she began, herself a secret "experiment" whose conclusion is yet to be.

Through Emilie's reflections, notes, diaries and disasters, THE ALCHEMIST'S DAUGHTER takes you from the glories of the Age of Enlightenment to the foul underside of British 18th-century life, and everywhere in between. It's a page-turner with startling beauty and substance that takes the strange alchemy of a confused and confusing time and refines it into true gold. This is easily Katharine McMahon's best work yet.