The Amnesia Clinic by James Scudamore (2006) pub.Harcourt

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A story of two schoolboys in Ecuador, one a 15-year-old British ex-pat the other the son of  a wealthy Ecuadorian family who lives with his uncle. They challenge each other by telling preposterous stories with Fabian's stories a form of bragging about his family. Fabian lives with Uncle Suarez in a gated compound and on visits there Anthony enjoys the licence to drink and smoke given to Fabian - as long as they don't go too far - which is what permissive adults usually say and not helpful!
Throughout there is some mystery about Fabian's parents. They were involved in a road accident and it seems that his father was killed. Fabian seems to believe that his mother is still alive. When Anthony comes up with a tale

that there is an Amnesia Clinic far away on the coast of Ecuador where Fabian's mother may be recovering the Ecuadorian boy persuades his British friend to go with him on an expedition to find her. This confusion of fact and fiction has dire consequences ..........the story is a reminder that while fancy may be free, in real life somebody has to pay.