The Brothers Lionheart by Astrid Lindgren

Jonatan, a hero among the Thorn Rose Valley people, is intent on freeing Orvar, the leader of the Thorn Valley resistance movement who is kept in the cave of Karmanjaka near the Karma Falls, where Katla dwells, with his release sparking the long-anticipated final uprising against Tengil. It turns out that Mattias is part of the Thorn Valley resistance and a friend of Jonatan, who is hiding in his house.

After arriving at a village, Karl throws himself into the arms of the first old man he encounters when he sees white pigeons with him, and surprisingly the old man - by the name of Mathias - takes him in without question. Soon after Jossi leaves, Karl is discovered by the soldiers and taken to the Wild Rose Valley after claiming that he lives there with his grandfather. Prompted by a nightmare in which he sees Jonatan in danger, Karl follows him in the middle of the night but while hiding in a cave, he witnesses a clandestine exchange between two of Tengil's soldiers and Jossi, who has turned traitor to his people. Soon after Karl's arrival, Jonatan leaves to assist the Thorn Rose people. The people of the Cherry Valley, led by Sofia, are aiding the resistance movement in the Thorn Rose Valley, but they know someone from the Cherry Valley is helping Tengil, as Sofia's white doves, which transport secret messages between the valleys, are being shot. The adjacent valley, the Thorn Rose Valley, is suppressed by a tyrant named Tengil, his army and a female dragon named Katla, who is controlled by Tengil through a trumpet. However, despite first appearances, not all is truly at peace in Nangijala.

Karl is introduced to the denizens of the valley, particularly Sofia the dove-keeper, Hubert the hunter, and Jossi, a landlord, and assumes the surname Lionheart along with his brother. Karl is crestfallen over his brother's death, until, just before his own demise, he receives a sign which allays his fears of death, and when he wakes again, he finds himself in the Cherry Valley of Nangijala, where he is happily reunited with Jonatan. Jonatan takes Karl on his back and jumps out of the house's window to save him, but dies himself in the fall. One day, a fire breaks out in the Lejon home.

His adored big brother, 13-year-old Jonatan, calms him down and tells him that in the afterlife, all men will go to a land known as Nangijala. In an unnamed Swedish city, ten year-old Karl Lejon has found out that he is going to die from an unspecified pulmonary disease (most likely tuberculosis).

The Brothers Lionheart by Astrid Lindgren