It is a didactic reading for pupils in the intermediate and upper cycle of Primary Education.

A theft in the Cathedral and its consequent investigation by grandfather Maranya are used to unveil daily life in Tarragona. It is an ideal previous work to be performed before "Let's discover the secrets of the Cathedral". Grandfather Maranya examines many characters and typical places in the Cathedral to find the thief.

We start with some advises for a good reading and at the end, we include several didactic proposals, chapter by chapter, on linguistic and historical aspects, which helps our comprehension of the text. Besides, we add a reading worksheet and an annex on activities to identify its parts and architectonical elements. A glossary completes this work, with the most complex artistic terms.