In the English countryside, a teenage farm boy, Albert Narracott, watches in amazement as a female horse gives birth to a healthy male foal. Over the next few days, Albert attempts to bond with the newborn animal until the creature is hauled off to an auction in town. Albert's father, Ted, a drunken, down-on-his-luck farmer, is also extremely taken with the horse. At the auction, he engages in a ruthless bidding war with Lyons, the richest man in town. Ted wins the horse after putting a bid in for an outrageous 30 guineas. Unfortunately, back at home, Ted's wife Rosie is outraged by her husband spending so much money on a racing horse, not a farm horse like they need. Although Albert steps up and promises that he will properly train the horse to plow the fields, Rosie is inconsolable, believing the family will soon lose the farm. Naming the horse Joey, Albert quickly earns the thoroughbred's trust. Albert even devises a unique calling system – blowing through his hands to mimic the call of an owl – to have Joey follow him everywhere around the countryside. But, when Joey refuses to allow a plowing collar be placed around his neck, an angry Ted pulls a shotgun on the poor creature. Albert bravely jumps in front of the gun's barrel, saving Joey's life. Although Albert does get Joey to wear the bulky harness, the Narracott farm is a rocky, inhospitable terrain. Albert and Joey try to work the field, but the plow can barely scrape the dry earth. Worse, Lyons, who is also the Narracott's landlord, and several townspeople show up to watch Joey's failure. Then, a rain begins to fall, loosening the dirt. Albert continues to push Joey hard and, at last, the plow successfully tills the field. The rain grows into a raging downpour and, in a few hours, the entire field is fully plowed. Although he's achieved victory, Albert rages that his father is a useless drunkard who almost shot the prized beast. Surprisingly, Rosie leaps to her husband's defense, explaining that Ted, who has won several military medals and ribbons, only drinks to forget the horrors of war. After the Narracott farm grows a plentiful crop of turnips, another massive rainstorm hits and the raging waters completely wipe out all the freshly grown vegetables. Unable to pay Lyons his rent, a desperate Ted sells Joey to the army behind his son's back. England has just gone to war with Germany, and Albert tries to enlist so he can stay with his horse, but he is too young. Capt. Nicholls, who has just bought Joey, promises to look after the horse personally and to return him home safely when the war is over. As Joey is led away with the soldiers, Albert ties one of Ted's military ribbons to the horse's reigns and swears that they will be reunited one day. At an army training base, Joey is placed in a stable next to a large black stallion named Topthorn. The two striking animals bond immediately, with Joey handily besting Topthorn during racing exercises. Their real test comes soon enough, though, when the British plan an early morning sneak attack on an unarmed German encampment. With their swords held high, the British soldiers ride Joey, Topthorn and dozens of other horses into the German camp. While many half-awake Germans are cut down by the galloping British, others dash off to the nearby forest. Lying in wait are several machine guns, and the Germans indiscriminately shoot at the horde of British attackers. While Joey makes it safely through the barrage of bullets and Topthorn is similarly unharmed, the same cannot be said of Capt. Nicholls and most of the other horses are killed and their corpses lay in the field alongside the men who rode them. Two earnest, young German soldiers, brothers Gunther and Michael, suggest to their superior officer that instead of just killing the surviving horses perhaps Joey and Topthorn could be used to pull the wounded off the battlefield. Topthorn stubbornly refuses to have a collar placed around his neck, but Joey smartly shows his ebony friend that he has nothing to fear from the harness and the two animals are soon pulling a wagon turned into a makeshift ambulance together. Back at camp, Gunther is ordered to stay behind and tend to the horses while Michael is to advance to the front with the other soldiers. As Michael marches out with his comrades, Gunther ties Ted's war ribbon to his brother's backpack allegedly for good luck. But, as the soldiers march away down the road, Gunther rides up with Joey and Topthorn and spots Michael out of the crowd by the ribbon. Gunther yanks his brother up and the two ride away in the opposite direction. Finding solace in a remote windmill, Gunther and Michael try to get some sleep. Their solace is interrupted when the Germans uncover their hiding place and shoot the boys for desertion. The horses are then found by a young French farm girl, Emilie, who lives close by with her elderly grandfather. A sickly girl, Emilie is entranced by Joey, which she renames Francois, and attempts to train him to jump, which he refuses to do. Soon, another contingent of Germans arrive and ransack Emilie's farm, but the girl is able to keep the horses hidden in the farmhouse attic. The deceit doesn't last long, however, and the Germans confiscate the two horses when Emilie is out riding the next day. Topthorn, who is nursing a severely wounded leg, is chosen first to pull an impossibly heavy German cannon up a steep hill. Sensing his friend's danger, Joey rushes ahead and takes Topthorn's place. Despite his legs constantly threatening to buckle, Joey successfully pulls a large cannon to the top of the hill so that it can be fired at the nearest village. In that village is Albert, now old enough to serve alongside his countrymen. Amidst the heavy, constant barrage of artillery, Albert and his fellow soldiers race across the barbed wire filled battlefield to meet the Germans head on. With a steady arm, Albert takes out a German fortification with a grenade. But, the victory is short-lived when a cloud of poisonous gas descends on Albert and the other soldiers. Further back from the frontline, Topthorn's leg wound gets the best of him. The once mighty animal lies down and dies. Left alone, Joey madly races through the battlefield trying to find safety. Instead of jumping over the barbed wire fences, he dashes directly through them until he's so entangled he can't move at all. Through periscopes held out over their respective trenches, both British and German soldiers spot Joey cowering in the field. One soldier each from both sides come out and, working together, cut Joey free from the painful barbs. Flipping a coin to see who will retain ownership of the horse, the British soldier wins the toss. Returning to camp, Joey is led right past Albert, who cannot see his equine companion since his eyes have been severely damaged by the gas attack. However, word reaches him that a "miraculous horse" has been saved. A doctor declares Joey too wounded to be saved and orders him to be put out of his misery. A crowd gathers as a sergeant points a pistol at Joey's head. But, the hooting sound of an owl is heard in the distance. The crowd parts, revealing Albert calling for his pal. Describing Joey's unique white markings, he convinces everybody that the horse is his. Reluctantly, the doctor agrees to treat Joey just like any other wounded soldier. When the war ends, Albert is told that Joey is to be sold at auction. The good news is that all the other soldiers pool their money so Albert can win the auction. The bad news is that Emilie's grandfather appears to make an outrageous bid on Joey, easily trumping Albert's small stack of cash. Although Emilie has died, the old man wants Joey as a reminder of her. Albert graciously gives Joey up, but the old man is touched by how much the boy and the horse appear to care for each other. The grandfather then reveals that he has Ted's military ribbon and releases both the ribbon and Joey to Albert's care. Returning home to their farm, Albert and Joey are greeted warmly by Rosie and the proud son at last returns the much-travelled war ribbon back to his father.