Said premise is that merpeople, here called deepsmen, exist, following the ocean currents in nomadic tribes, vulnerable to human contraptions like fishing nets, but also capable of ripping apart most sailing vessels. In the 9th century, an alliance was struck between deepsmen and the city of Venice. A human-deepsman half-breed named Angelica secured the city's naval superiority by directing her tribe's attacks on the foreign fleets besieging it, married the Venetian Doge, and dispersed her children and grandchildren among the royal courts of Europe. For a seafaring nation, a ruler with deepsman blood, who could secure the protection of their local tribe and direct them to attack the fleet of their nation's enemies, quickly became a necessity. Whitfield constructs a world in which royalty is less a social or political construct than it is a function of biology, with characters often referring to the physiological attributes of hybrids, such as their vertebrate legs (actually bifurcated tails) as the attributes of royalty. This simultaneously strengthens and weakens the position of the royal families, who on the one hand can't be ousted by power-hungry but fully human nobles, but on the other hand are vulnerable to attacks from any sailor's bastard (a word which in Whitfield's novel is applied exclusively to non-royal half-breeds), or from hybrids deliberately created by those same nobles. The conception or concealment of bastards is thus outlawed and punishable by death--a sentence which is also applied to the hybrids--but as the decades and centuries pass the royal houses of Europe become more and more interbred, until a healthy, sane, and fertile royal is the exception rather than the rule, and by the time the novel opens (an exact date is never given, but the setting feels 16th-17th century) are so weak as to be ripe for the picking.
Into this world come our two protagonists, Henry and Anne. Henry is a bastard, raised for the first five years of his life underwater with his mother's tribe, then abandoned on the English shore when he--weaker and slower than full-blooded deepsmen--becomes too troublesome for his mother to protect and care for. He's found by a scholar named Allard, who brings him to the attention of Lord Claybrook, a high ranking courtier who has his eye on the English throne. Anne is the youngest princess of the failing English royal house. Her grandfather Edward, the current king, is old, and though her father William is healthy, the heir presumptive is his brother Philip, a physically and mentally handicapped dead end. William tries to secure his line's survival by marrying the Romanian princess Erzebet, but their union produces only daughters--Anne and her older sister Mary--and though Mary is entirely healthy and mostly human in her appearance, Anne is a genetic throwback whose face is phosphorescent (later revealed to be an attribute of deep-dwelling deepsmen tribes), and in the atmosphere of panic created by Philip's birth, is soon rumored to be retarded herself. When William dies, both the court and England's relations with its deepsman tribes are left in Erzebet's hands, and when she dies under mysterious circumstances the responsibility for the latter devolves to Anne and Mary, then only in their early teens, while their grandfather searches desperately for acceptable husbands for them who will ensure England's stability and the continuation of the royal line.
The first two thirds of In Great Waters are spent following the childhood and very quick maturation of its two protagonists in two parallel plot strands. Like a lot of authors who throw children into settings rife with politics and intrigue, Whitfield makes both of her protagonists much too savvy, observant, and intelligent to be believable, but she rather cleverly draws attention to this fact, and explains it by making it a component of Henry and Anne's inhuman ancestry. Henry, we're told in the novel's very first sentence, "could remember the moment of his birth," and from that moment until he's abandoned on land it's clear that deepsmen development is much faster than the human kind, that Henry is expected to learn how to fend for himself and function in the tribe much faster than a human would. It's also made clear that this accelerated development also expresses itself in a chilliness in both Henry and Anne's natures--they are both, quite literally, cold fish, regarding others less with fuzzy mammalian attachment than in coldly utilitarian terms. Anne's sister Mary is her rival for Erzebet's attentions, and even at four years old Anne calculates whether to accept Mary's friendly overtures or work against her, while five year old Henry plays games of dominance and control with Allard. (Mary, meanwhile, is a great deal more affectionate but also less ruthless and politically savvy than Anne, and it's one of the novel's few missed opportunities that it does relatively little with her, and doesn't fully mine the differences between the sisters nor explore the suggested correlation between Mary's more pronounced humanity and her more human appearance.)
What's most interesting about In Great Waters is how it stresses that, despite my comments above, the tension between compassion and unsentimental pragmatism doesn't parallel the division between human and deepsman, that though the humans profess to love their fellow man and desire mercy and forgiveness, Anne's civilized background embodies that tension just as much as Henry's savage one. Deepsmen society, as seen through Henry's eyes at the beginning of the novel, more strongly recalls an animal pride than a human tribe. Deepsmen have no crafts, agriculture, or animal husbandry, and very nearly no history, art, or culture. Tribes are run by a strict rule of the survival of the fittest, and the protocols for establishing their hierarchy are clearly modeled on the natural world--males fight in single combat over females or leadership, and excess young men are often driven out of the tribe. Henry's expulsion from the tribe is an example of these protocols in action, and once on land he continues to act them out, challenging Allard and the other humans he encounters to fights in order to prove his dominance, and reacting with puzzlement when it's assumed that he feels a son's love and attachment to Allard and his wife. At the same time, Henry recoils in disgust from the political machinations Claybrook sets in motion in order to put him on the throne. He's more than willing to kill King Edward in single combat, but doesn't understand why an army must be assembled, and perhaps killed, to resolve what should be a simple test of strength, or why another bastard child, discovered several years after Henry is, must be put to a cruel, torturous death even though it is too weak to fight. The death of the bastard child is the crux of the novel for Henry, but it is also so for Anne. Raised in the bosom of civilization, her life proscribed by ritual and tradition, her time spent studying languages and rhetoric (while Henry adamantly refuses to learn how to write or speak a second language), Anne nevertheless finds herself struggling with the same questions as Henry when faced with the child's execution. "Should we be merciful to our enemies?" She asks Erzebet, and finds no good answer.
If there is a complaint to be leveled against In Great Waters, it's that sufficient sparks fail to fly when Henry and Anne finally meet, and that the last third of the novel, in which they join forces in order to secure England's future, is a bit of a letdown. The two clash marvelously against one another in their first few encounters, matching wit for wit and unflappable calm for unflappable calm, but once the obvious alliance is made (for some reason, the idea of marrying Henry to Mary or Anne never occurs to Claybrook) the novel goes a little slack. One almost suspects that Whitfield was undone by her desire to undermine the romantic expectations that her setup creates--if the bulk of your novel follows the parallel and equally unhappy stories of two chilly, pragmatic young people of opposite genders, it almost seems required for their meeting to result in a searing romance--and though I can understand that desire (and indeed, given how poorly handled the romance in Benighted was, applaud it), I think that Whitfield couldn't quite come up with a suitably exciting substitute for it. Romantic or not, the final meeting and partnering up of Henry and Anne should have been explosive. Instead they become slightly nicer and more accommodating towards one another, for no reason other than the same political instincts that have driven them throughout the novel, which now tell them to appease each other.
Still, there is much to enjoy in those chapters of In Great Waters in which Henry and Anne play off each other. The two see the world in such completely opposed terms that their interactions are almost dizzying. Anne is devout, and derives much of her morality--which ultimately drives her to save Henry from the stake--from her Christian faith. When Henry learns about Christianity, however, he is appalled: "The landsmen weren't just strange. They were stupid, bone-deep stupid. They were mad." The same resistance to the Christ story and its inherent irrationality is also what makes it clear to Henry that the story of Angelica's miraculous emergence from the sea just as the people of Venice needed her most is a political fabrication, and unlike humans he lacks both the ability and the desire to overlay reality with narrative.
It struck Henry, listening to Westlake tell his stories, that the nastiness of the landsmen's possessions, the straight lines and enclosing roofs and binding clothing, could be explained by this. They didn't notice them. They looked at clothes and thought of ceremonies; they looked at buildings and thought of their owners. Always the ideas, and never the things themselves. They couldn't feel what was up against their skin; the world, thriving and struggling and vitally, irrefutably real.What's best about In Great Waters is how fully in layers these two worldviews--Henry's materialism, Anne's spirituality; the savage, animalistic mindset that sees no purpose in intangibles, in language that is anything more than utilitarian, in social constructs that extend beyond the tribe and beyond the moment, versus the human tendency to create complex, pie-in-the-sky structures, which gives us history and art and culture and science, but also cruelty and war and needless slaughter--until there's no choosing between them. By the end of the novel all that's left is to accept, as Henry and Anne do, that they are fundamentally of two different species and will never truly understand one another, and yet it's precisely out of that alienness that they manage to find room for the compassion that has eluded them for so much of their lives, each rejecting just enough of the ideas they've grown up with while still remaining true to themselves. At several points during my reading it occurred to me that In Great Waters, with its emphasis on court politics and its period setting, might appeal more to readers of historical fiction than to genre fans, but it's this ending and the light it casts on the events of the novel that shows how perfectly suited it is to the latter group--it is a pitch-perfect, and utterly persuasive, description of the meeting and coming to terms of humans and aliens.