The summer begins for cousins Tecumseh and Lum, and it seems fairly ordinary. Another summer for them to spend with each other and Tecumseh's dog, Soldier, on the Bright Water Reserve in Alberta and across the river within the Montana town of Truth. But quickly, the pair finds that their summer takes a dark turn. A mysterious woman with a suitcase is seen throwing things into the river, before jumping in herself. Stranger though is when the cousins try to find help, they see that she and her truck have disappeared. Other mysteries begin to plague the summer, as Tecumseh worries about his own family concerns. His parents' marriage is consumed in turmoil, his rolling-stone aunt refuses to stay put and the safety of Lum is threatened by his abusive father. As Truth and Bright Water prepare for the Indian Days festival, the cousins' secrets come together in a climax of tragedy, reconciliation and love.