Tellería is a fictional 700 years old town that politically belongs to the Automous Community of Castilla-León despite to be located in the Basque Country (north to Spain), which inhabitants want unsuccessfully to change of community from Castilla-León to Basque Country from much time ago. In the same day that Antolín, town's mayor, makes a new attempt just to learn that it was rejected again, his son Gorka back to the town with his job partner and love interest Yolanda to investigate town's church past, managed by town's priest Don Anselmo. When by chance Yolanda falls to the under ground due to the unfinished works made by well-known historian and archaeologist Peio, she finds a medieval sepulcher, discovering that it's the tomb of Walter Tell, son of legendary Swiss hero William Tell. Finding an ancient documents that prove the creation of Tellería (Tellstadt in English and rest of languages) as a gift given to Walter Tell after his help to the King of Castile Alfonso XI in a battle, it creates an incredible possibility: ask Switzerland to accept Tellería as its own to be the 27th canton. Gorka meets with Antolín and his mother Anamari to tell it, but he meets too with Nathalie, Antolín's right-hand and Gorka's former girlfriend, causing a doubt in him about the girl he loves. Looking for the tax advantages if Tellería could be part of a tax haven as Switzerland, the news spreads quickly along Spain, and the town tries to adapt itself as fast as be possible hoping the incoming visit of Switzerland's President to verify if Tellería has the necessary to be part of the country. But the new situation causes the resentment of town's banker Añibarro, who advocates for that Tellería be Basque, and hostel's manager and Nathalie's father Revuelta, who advocates for that Tellería be Castillian. In addition, photographer and Yolanda's boyfriend Fernando suddenly arrives to the town, causing more troubles than solutions after Yolanda discovers that Fernando really is an agent of CNI (Cuerpo Nacional de Inteligencia or National Corp of Intelligence; Spanish equivalent of FBI), sent to the town by the suspects of a possible riot by weapons trafficking (in true a personal collection of Don Anselmo). When the love triangle between Gorka, Yolanda and Nathalie is known by foolish and aspiring sculptor Íker, Gorka's best friend and Añibarro's son, who is falling in love with Nathalie and desperately tries that she loves him, Íker learns that Revuelta and Añibarro have left behind their differences and he joins them in a plan to revenge of Gorka and put end to the Antolín's ambitions.