The following version of this book was sued to create this study guide: Mulligan, Andy. Trash. New York: Ember, 2011.

In an unnamed third world country, Raphael, Gardo, and Rat (Jun-Jun) are three trash boys, living in squalor and spending their days picking through hordes of garbage in the hopes of finding something salvageable. Their section of the city is known as Behala, and despite the presence of the Mission School, a charitable attempt to provide education to the children of the slum, the boys are urged into working as a means of supporting their limited families, as Raphael lives with his aunt, Gardo with his uncle, and Rat lives alone, having come from outside the city, and unknown with no family who is constantly picked at by other children. One day, Raphael finds a leather wallet with eleven hundred pesos, two pictures of a small girl in a school dress, an ID belonging to a Jose Angelico, a folded map, and a key. Splitting the money with Gardo, Raphael attempts to get on with his life until the police visit, looking for the wallet. His aunt accidentally reveals that Raphael found something, which he attempts to dance around when questioned by the police. While the police offer ten thousand pesos to any who might have found the wallet, Raphael and Gardo keep their secret close, asking Rat to hide the wallet since he is never visited by anyone. Rat reveals that the key belongs to a storage locker at the railway station, where he lived for a while. Despite the danger of the police lurking around, who have commissioned the entire Behala populace to help them with their search, the boys go to the railway station to retrieve the package, which turns out to be a letter addressed to a Gabriel Olondriz and a slip of code.

The boys then turn to the Mission School, using the computer there to research Olondriz, keeping their search a secret from Father Julliard, the head of the school. When they return to Behala, their homes are ransacked by the police and Raphael is arrested and taken to the police station. While there, he is beaten viciously, threatened with death if he did not reveal the whereabouts of the wallet. Despite the threat, Raphael does not divulge and is eventually let go, managing to find his way home. After his return, the boys agree that they cannot stay in Behala longer, and move on to solving the puzzle of the letter. With the knowledge that Angelico had been murdered by the police for stealing six million dollars from the vice-president's house, where he worked as a houseboy, they approach Grace Olive, a foreign volunteer at the Mission School, and trick her into taking Gardo to the main prison to see Gabriel Olondriz, by feigning that Gardo needs to see his grandfather in order to save his house. Grace takes Gardo with her, spending her money on buying him new clothes and bribing her way Olondriz. While there, Olondriz reveals Gardo's lie and speaks at length about his crime. He was imprisoned for bringing corruption charges against Senator Zapata, the vice-president from whom Angelico had stolen the money. When Gardo reveals the contents of the letter addressed to Olondriz, the latter becomes excited, saying the code is familiar to him and that he needed his Bible. Before he can retrieve the Bible, the visit is cut short by a guard named Marco, who agrees to give them the book later.

While Gardo is at the prison, Raphael and Rat travel across the city, sneaking into Senator Zapata's house, where they learn from a gardener that Angelico stole the money and took it out in a broken refrigerator. Rat reveals to the other two that he has some significant savings, which he wants to use to return to his home in Sampalo, a distant city where he had grown up fishing. With his money, the boys run away from Behala before the police can catch them, as Gardo was photographed at the police station. Realizing that they need Olondriz's Bible to solve the code. Gardo returns to the prison and follows Marco, striking an agreement with him for the Bible in exchange for money, which Rat steals from the Mission School, leaving a note with his name on it. During the meeting, Marco attempts to grab Gardo as part of the set up, but he manages to escape. Returning to their temporary apartment, they stay up all night, finally solving the riddle. The code turns out to be a book code, the numbers corresponding to pages and letters, and leads to a grave in the city's cemetery. The following morning, they manage to escape just as the police try to surprise them, hiding amongst a group of street boys before hailing a cab to the cemetery, just in time for the Day of the Dead festivities.

While there, they realize that the grave belongs to Pia Dante, Angelico's daughter, who turns out to be alive and waiting close by. While they feed her, the boys break open the gravestone and find the six million dollars packed in. Instead of keeping all the money, they come up with an alternative. They return to Behala, and Rat returns the amount he stole to the Mission School safe, taking some school uniforms and school bags with him in the process. They stuff money into their bags and throw the rest into the wind, for anyone in Behala to retrieve. Blending in with other school children in uniform, the three boys and Pia Dante manage to find their way to Sampalo, finding happiness in fishing and the simplicity of their life.