This documentary explores the history and tradition of one of the most international sauces in Basque cuisine. We travel the world to discover the countless recipes and anecdotes associated with the sauce and its ingredients, from a delicacy served in royal households and embassies to a dish prepared on the most humble coal-burning stoves. We look at the ingredients and where they come from, and the different theories about the very first recipe recorded under that name and its different variations. The documentary also examines the impact on Basque cuisine of the various socio-cultural revolutions that have taken place over the years, including religion, geographical characteristics and the products they have propitiated. The role of women in passing down traditional dishes and the fusion of these dishes with modern cuisine in affluent households are also analysed as factors that shed enormous light on cooking and food today. A witness to all of this, Biscay sauce remains as present as ever, from the most avant-garde tables to family celebrations in the most traditional settings.