Paulo is a ten-year-old boy who lives with his parents and his grandfather. His father spends all his time talking on his mobile phone. The record number of minutes he has spent talking without stopping is twenty-three. For this reason, he gets a red ear and doesn’t like it when his son points this out to him. On one occasion, his father went to the bathroom, and Paulo hid the phone under his bed. His father was furious and blamed his mother. Paulo’s grandfather found it all quite amusing. When Paulo’s father said Paulo behaved just like him, he answered that there was nothing strange in his behaviour – just ask his brother Bernardino. The trouble is, according to Paulo’s father and mother, this brother Bernardino doesn’t exist. Paulo’s father works until eight in the evening but, even when he comes home, he continues receiving work-related calls and barely pays the others any attention.

Paulo’s grandfather forgets that he has said something. He sometimes doesn’t recognize his own son and calls his daughter-in-law “madam”. The only person he doesn’t forget is Paulo, although he does call him Sinbad and ask him to approach on his ship and save him from these filibusters. When Paulo jumps on to the sofa – his ship – his grandfather laughs a lot, and his teeth fall out or, when he waves his arms about, he knocks things over. Then Paulo’s father tells Paulo to go and play with children his own age, but Paulo finds it much more fun to play with his grandfather. When he tells his grandfather he’s fun to play with and not like other people, his grandfather becomes serious and looks out the window at Bernardino’s house. Paulo has heard he has Alzheimer’s, but he doesn’t really understand what this is.

Paulo’s father says his grandfather goes through ‘difficult periods’. Paulo’s mother finds this hard to deal with, such as when he sits in front of the telly when it’s switched off, wanders about the house, gets up at night and turns the telly on loud, empties the fridge and spills the contents on the floor, or shouts at himself in the mirror. Paulo asks his father about the illness. He says people suffering from Alzheimer’s sometimes don’t remember things or behave strangely. Sometimes they behave like children. When Paulo’s mother goes out, then Paulo and his grandfather play at being Sinbad and the Captain of the Seven Seas (Paulo wonders who is captain of the other three seas on the planet). Paulo’s grandfather asks to be rescued, or they hide things in the house, which they call treasures. Everything is fine until one Sunday in February when they wake up and Paulo’s grandfather is no longer there.

Paulo’s parents inform the police that his grandfather is missing and go out to look for him. Paulo stays behind – his father says he’s too young to go searching the streets – and spends the day with his best friend, María, a girl who lives in the flat downstairs. He feels very sad when his parents return at the end of the day and still haven’t found him. He can’t understand why he would disappear like this. His grandfather’s disappearance occurs two weeks before Carnival, when Paulo plans to dress up as Sinbad, with a turban and a scimitar, but when the day arrives, he doesn’t feel like it. His mother asks his father to talk to him because he’s behaving strangely (who wouldn’t if their grandfather had disappeared?). Paulo asks his father to tell him his grandfather’s favourite story, Sinbad the Sailor, but his father, who does his best to ignore some calls on his mobile phone, gets some of the details wrong and says he can’t waste time telling him a story he’s already heard a hundred times, he has more important things to do, he has responsibilities. Paulo becomes angry with him because he never spends enough time with him, he always has work to do, and in the end he dresses up as Sinbad to attend Carnival and do battle against some filibusters outside.

A month later, the police give up their search, and Paulo tries to carry on as normal. One day, he is playing football outside with María and her three-year-old brother, Xavier, when the postman arrives with a letter for Sinbad from the Captain of the Seven Seas. Paulo is so surprised he lets in a goal by Xavier, even though the boy can’t play football. He rushes upstairs to open the letter in the privacy of the sitting room. In it, his grandfather asks what a Captain of the Seven Seas would do if people were trying to sink his ship – he would escape. Life is an adventure, and there are filibusters everywhere, even on board one’s own ship. He tells Paulo to search for him in the Pirate’s Tavern and encloses a tiny key. Paulo searches for ‘Pirate’s Tavern’ in the telephone directory and can’t imagine what such a tiny key could be for. Over lunch, he asks his parents if they’ve heard of the Pirate’s Tavern (without telling them about the letter). His mother drops her glass on the floor, and his father almost chokes on his spaghetti. They are obviously both very nervous. His father claims that this place does not exist and says he can’t eat any more, he’s going out. His mother says Paulo is not to blame for what has happened and urges him to finish his spaghetti.

After lunch, when his father has returned to the office, his mother enters his grandfather’s room to dust his books. She is dusting one, very large book – which turns out to be Sinbad the Sailor – when Paulo notices a small, rectangular box behind it. He surreptitiously takes the box out of his grandfather’s room, runs down the stairs of his block and inserts the tiny key his grandfather has sent him with the letter. It opens at the first attempt.