Diego Michele (Carlo Lupo) is a young Italian teenager with big problems both at home and in school. His weak-willed mother ignores him and his stepfather beats and abuses him. At his local high school, his classmates are pressuring him to become involved in criminal activities. Seeing that his mother of low self-esteem doesn't understand him or his unhappy feelings, Diego runs away from home.
Diego takes a job at a garage run by auto mechanic Anselmo (Fiorenzo Fiorentini). After only a few days of working there, Diego accidentally causes some damage to a car which is in for repairs. Diego runs away from the garage fearing Anselmo will report him to the police.
A few days later, Diego meets Marco (Luigi Diberto), the flamboyantly gay coach of a swimming team who takes him on as an assistant warden at the local pool. Diego's passion for swimming pushes him to train at night when the pool is closed. It is during one of these solo nighttime sessions that Marco sees Diego swimming laps and recognizes the boy's potential as a championship swimmer. The president of the sports club (Jacques Sernas) hears about Diego's swimming prowess, and allows him to join the team where he soon becomes the team captain, provoking the envy of the other athletes.
Diego's first swim meet is when he takes part in the Italian junior championship and wins first place, which overjoys Marco and his younger sister Claudia (Vittoria Galeazzi) whom begins to have strong romantic feelings for Diego since meeting him in a low-key way earlier when he was hired by Marco. But soon after the championships, Diego falls ill. Hospital tests diagnose a terminal illness in the form of a rare type of leukemia. Determined to conquer his illness at any cost, Diego continues to go to the hospital for treatment while training for more swim meets when he reacts positively to the treatments. But as time goes on, Diego finds that he has less and less energy, and becomes aware that he will die. The doctors advice Diego against continuing his competitive activity, but the boy nevertheless insists and obtains permission from Marco to participate in one last grand event of his life, the European Championships in Amsterdam.
In preparation for this, Marco takes Diego to his country house where he puts him though a rigorous training program, despite knowing about Diego's illness. Here, Diego is reunited with Claudia, who finally reveals her romantic feelings for them, and the two of them fall in love, with Marco's approval. She oversees his training and even when Diego goes to the hospital for further treatment, she gives him a blood transfusion to help him gain some of his energy back.
Diego, Marco, and Claudia travel to Amsterdam with Diego fully confident in his ability to take on the challenge of the great race. On the day of the big championship, Diego starts off the race in spectacular fashion where, in the first few lengths, he wipes the floor with the opposition. But gradually, his illness makes itself felt and he slows down swimming. The crowd, aware of his health problems, continue to cheer him on while his swimming becomes more labored. One by one, the other swimmers overtake Diego, but he does not give up and continues to swim, floundering until he completes the race in last place and to a standing ovation from the spectators. Diego emerges from the pool and is embraced by Claudia, and then collapses to the ground exhausted. Diego tells Claudia and Marco that it was never his intention to win, but to show that he could still make the entire course to prove himself. Diego, aware that his days are numbered, slowly walks out of the arena to live out his last days in peace with Claudia.