Fawn is a farmer girl who has married Dag, a patrolman of the Lakewalker people. His people have tried to annul their marriage on the basis that Lakewalkers have a form of magic called groundsense and farmers do not, therefore a mixed marriage is invalid.
Because of this Dag and Fawn have left his home at Hickory Lake with their horses and little else. Dag has decided that the gap between the two cultures needs to be bridged. He and Fawn are set to travel the land learning more about both and about the evil creatures named malices that threaten to overrun the world.
First they stop at Fawn's old home. He starts his mission there, explaining to her family about how groundsense works and pointing out that the assumption that it is restricted to Lakewalkers is false, many farmers have a little spark of it. He and Fawn also explain about malices, which a lot of farmers are skeptical even exist. Most importantly he teaches them to recognize the signs a malice is growing nearby.
Fawn's brother Whit begs his way into traveling with them, jealous of his sister's adventures. Fawn is reluctant since he has teased her mercilessly over the years, but eventually agrees.
As they travel Dag feels himself recovering from the injuries he experienced fighting a malice in the previous book. His groundsense is returning to him but he notices it is tinged with something darker from where the malice dug into him and left a bit of itself.
Whit is excited by all the new sights and curious about Lakewalkers. He is also a bit of a merchant, he sells his and his sister's horses and arranges a ride with a glass merchant to get them to the river. On the way Dag's horse accidentally injures the merchant's assistant, a boy named Hod and Dag uses groundsense to heal the him.
At the river Dag finds a Lakewalker patrol and visits them hoping to get a new sharing knife, a special Lakewalker weapon that is the only thing that can kill a malice. They recognize him as an exile and refuse him a knife, since those are only for active patrollers.
Meanwhile Fawn has found a boat called the Fetch that will take them down the river, owned by a woman named Berry. She is traveling with her uncle and her younger brother, and needs crew. Berry is looking for her missing fiance, brother, and father who have disappeared downriver. Whit immediately becomes infatuated with Berry and decides to come along, even though his original plan was to turn back home at the river.
After they set off they find Hod has stowed away, he is grateful to Dag for treating him kindly and for the healing, but soon Dag realizes that he has also accidentally beguiled the boy with his groundsense, he doesn't know how to undo it so he lets the boy come along.
As they sail they run into some Lakewalkers who demand to speak to Dag. Word of his healing of Hod has spread and some farmers brought a sick woman to them, demanding treatment. Traditionally Lakewalkers have kept their magic secret and they tell him to stop. Dag refuses and tells them they should share or trade, and also teach others to use groundsense.
The Lakewalkers scoff and accuse him of being a renegade, but he explains how malices have been growing right under farm towns because the farmers have no groundsense or even basic knowledge of malice spotting. They seem skeptical and warn him again to stop before they part ways.
Dag returns to the boat to find the sick woman has been brought there. He heals her and as he does he explains what he is doing to the gathered crowd, realizing he has a captive audience for his message of doing away with Lakewalker mystery.
Before they leave they pick up one more straggler, a Lakewalker youth named Remo who is in trouble for getting into a brawl and breaking his sharing knife. He has heard of the exile Dag and figures he doesn't want to return home so that's better than being along with non-Lakewalkers.
They arrive at the town of Silver Shoals and Berry goes into town to ask after the missing boat of her father. She is told that there have been many missing boats lately in the region of Luthlia, and that Lakewalkers are suspected, Fawn scoffs at the idea.
Dag and Remo, with some help from Fawn and Hod, experiment with their healing and their groundsense and Dag figures out how beguilement works, and how to get rid of it. As they travel Dag encourages the boy to mingle with the others. Dag is also experimenting with stranger magic, a form of groundsense called groudripping which is associated with malice magic, he is trying to figure out of it is inherently bad or just a different form of groundsense.
They run into a single Lakewalker on a small canoe and recognize Remo's friend Barr. He tells Remo he's been forgiven and wants to take him back, but Remo refuses choosing to stay on with Dag. After some trouble Barr eventually tags along with them.
They also pick up a couple of stranded villagers named Chickory and Bearbait.
As they continue south they run into a boat that offers to steer them through an upcoming rough patch. As they speak Dag notices one of the older men is beguiled. When they get nearer Berry recognizes one of the other men as her missing fiancee, Adler.
Adler claims his boat was sunk and he has been trying to earn back the money for a new one. Dag senses he is lying, and notices the other men seem very alarmed at encountering Lakewalkers. Dag unbeguiles the old man and he confesses that they are really bandits under the command of a Lakewalker named Crane.
Dag sends Chickory and Bearbait upriver to summon help from a boat they passed earlier and together the two crews raid the bandit hideout. They are successful and take the bandits prisoner, though Crane is nowhere to be found. Among the loot in the hideout Dag finds an unprimed knife. Remo is especially horrified by this since sharing knives are primed by a Lakewalker with their dying heartblood, and that means they would have murdered a Lakewalker without letting her prime her knife first.
Crane has snuck around the attackers and he takes over the Fetch, freeing Adler. Dag shows up and groundrips Crane's spinal cord paralyzing him. Helpless, Crane confesses his crime and Dag offers him an alternative; he can hang with the rest, or Dag will use Crane's heartblood to prime the knife.
Dag rededicates the knife and uses it to kill Crane priming it with his blood. He makes sure all the non-Lakewalkers see the whole process and explains exactly what is happening at each step, hoping this will help demystify Lakewalker magic a bit more.
Done with that the Fetch sails on downriver, Dag brooding over what he has seen and Whit trying to decide whether to express his love for Berry now that she is no longer betrothed. Dag wonders if Lakewalkers really can mix with outsiders, given their powers. Crane's control over others plus Dag's own groundripping makes him wonder if he was wrong all along and the old ways are best, Fawn tells him she still believes it can be done.
Eventually they arrive at the city of Graywater on a coastal delta. White hires a sailboat for them wanting to see the coast and the sea, and sensing they need some fun after the horrors upriver. They pack picnics and sail down to the beach and spend a day relaxing.
Dag and Fawn go walking along the beach and when they return to camp they find that Whit has proposed to Berry and been accepted.
The book ends with Whit and Fawn standing on the beach and contemplating the road ahead of them.
Best part of story, including ending:
The cast of characters introduced in this one give Fawn and Dag a bit of balance and it takes the story more towards adventure and worldbuilding and away from the initial romance.
Best scene in story:
I liked the discussion between Dag and Crane, where you can see how badly a renegade Lakewalker can become and why Dag is so worried about what he is doing.
Opinion about the main character:
Fawn doesn't get much to do in this book, she makes friends easily but otherwise she seems to mainly be there to anchor Dag, who is becoming the protagonist at this point.