The fourth installment in the
Ranger's Apprentice series opens in the mountains of Skandia, a northern warrior nation, where two young people from the kingdom of Araluen are hiding in a remote cabin. Will is an apprentice in Araluen's elite Ranger Corps, a force of skilled scouts and archers. He has only recently recovered from an addiction to warmweed, a mind-numbing drug administered during months of forced labor as a slave in the Skandian stronghold of Hallasholm. His companion Evanlyn, secretly Princess Cassandra of Araluen, nursed him back to health and helped him escape. The spring thaw signals that Skandian hunters will soon return, and the two must flee into the neighboring country of Teutlandt before they are discovered.
When Evanlyn goes alone to check their snare line, a Temujai warrior, a scout from the mounted steppe tribes of the east, seizes her and knocks her unconscious. He brings her to a camp of six warriors, where his unauthorized capture provokes a furious argument with the patrol sergeant, who decides Evanlyn must be killed to prevent discovery of their mission.
Will wakes to find Evanlyn missing. Weak and armed with only a crude hunting bow, he tracks her to the Temujai camp. At dawn, the sergeant draws his saber and walks toward Evanlyn. Will shoots the warrior in the exposed wrist, the only point his fire-hardened arrow can penetrate, and the sword drops. Two warriors charge Will, but from behind him a longbow thrums and black-shafted arrows kill both attackers. Will turns to see his mentor Halt, a legendary Ranger, in his gray-green cloak. Horace, Will's closest friend and a warrior apprentice, bounds forward and defeats the last attacker. The two have traveled from Araluen to rescue Will. Will sobs as he embraces Halt, who is surprised to find a tear on his own cheek.
Over a campfire, the companions share their stories. Will learns that Horace defeated the warlord Morgarath in single combat and became a celebrated figure in the western kingdom of Gallica. Halt is deeply troubled by the Temujai presence so far west. He explains that the once-disorganized steppe tribes were unified into a disciplined cavalry nation whose flag-signaling system allows centralized battlefield command. Twenty years earlier, they overran multiple kingdoms and halted only when a succession crisis recalled their armies. Now they have returned.
Near the border, Halt encounters Erak, a Skandian jarl (chieftain) and captain of a wolfship (longship) who had earlier helped Will and Evanlyn escape Hallasholm. Though initially suspicious, Erak accepts Halt's evidence that the Temujai, not Araluens, killed a Skandian border garrison. Halt proposes releasing a captured Temujai warrior and trailing him back to his army. He and Erak follow the freed prisoner to a valley filled with campfires: an invasion force of five to six thousand warriors. Skandia can muster at most two thousand.
On the march to Hallasholm, Erak asks Halt to serve as tactical adviser. Halt agrees but demands Erak's sworn protection for Will and Evanlyn, regardless of their status as escaped slaves or Evanlyn's identity. Erak gives his word. Oberjarl Ragnak, the aging Skandian ruler, accepts Halt's services with grudging respect. Ragnak's Vallasvow, a sacred oath to kill any relative of the Araluen King, remains a looming threat, though Evanlyn's identity stays hidden.
Halt theorizes that the Temujai want Skandia's wolfship fleet to control the seas and ultimately invade Araluen. He dispatches raiding parties that slow the advancing column from thirty kilometers per day to less than twelve. Will proposes a critical innovation: massed archers who raise their bows to four standardized positions while a single observer calls range. Erak produces a stockpile of captured Araluen longbows, and Halt persuades Ragnak to promise freedom to any slave who fights. One hundred volunteers step forward.
Will trains the archers, with Evanlyn calling out readiness from a sheltered trench when the men have reloaded and Horace commanding shield bearers who protect the line between volleys. Evanlyn also uncovers a plot by the wolfship captain Slagor to ferry 150 Temujai warriors behind Skandian lines. Slagor retaliates by revealing Evanlyn's identity as Princess Cassandra, invoking the Vallasvow. Erak steps between Ragnak and the princess, and Halt brokers a compromise: Since the vow specifies no deadline, Ragnak can postpone it until after the invasion. Will then devises a scheme to strand the 150 Temujai on a remote island by luring them aboard wolfships, removing them from the battle without a fight.
Halt selects a defensive position where the coastal plain narrows. His plan accounts for the Temujai's signature feigned retreat: Skandians will pretend to fall for the trap, then form a shield wall while hidden axmen attack from the tree line. Will's archers will fire from behind an earthwork berm protected by a trench and wicker breastworks.
The battle unfolds largely as planned. The feigned retreat is countered when the pursuing Skandians form a shield wall and the hidden axmen crash into the enemy's flank. General Haz'kam, the Temujai commander, orders a rolling assault. Will reveals his archers, and the first volley of one hundred arrows shatters a galloping Ulan, a cavalry unit of sixty riders. Will directs fire against successive units while dueling elite Temujai marksmen called Kaijin. Haz'kam's deputy Nit'zak breaks through the Skandian line protecting Will's position. Horace leaps down to fight, and Will, out of arrows, draws his knives beside him.
Nit'zak advances on Evanlyn in the trench, saber raised. She turns, meets Will's eyes, and smiles a farewell. Will spins his heavy saxe knife and throws it, killing Nit'zak before the blade falls. Ragnak charges into the breach in berserker fury while Halt arrives with his longbow. On the opposite flank, Erak leads a devastating flanking attack. Haz'kam, calculating that further losses will strand his army in hostile territory, orders a general withdrawal.
Ragnak dies amid his enemies, having sustained over fifty wounds. After three days of mourning, Erak is elected the new Oberjarl. Halt proposes a five-year mutual defense treaty: Araluen will station archers in Skandia seasonally, and Skandia will cease attacks on Araluen. Because Halt's banishment from Araluen has stripped him of authority to sign, Evanlyn steps forward and signs as Princess Royal.
Erak sails the Araluens home. At Castle Araluen, King Duncan welcomes them. Halt remains aboard, noting that three weeks of his year-long banishment still remain. Erak requests a pardon as a diplomatic gesture to seal the treaty, and Duncan grants it. Crowley, Commandant of the Ranger Corps, presses a silver oakleaf insignia into Halt's hand, restoring his rank. At a grand banquet, Horace is knighted as Sir Horace, Knight of the Oakleaf. Duncan offers Will a commission in the Royal Scouts, but Will declines, choosing to complete his Ranger apprenticeship.
Will's relationship with Cassandra has grown strained; restored to royal life, she is surrounded by courtiers, and the social gulf leaves Will tongue-tied. As Halt and Will ride toward home, Cassandra watches from a castle terrace with tears in her eyes while Horace places a comforting arm around her shoulders. The morning sun washes Castle Araluen in pale gold, but Will is riding south and does not notice.