In recent years, Allegretto Nuzi has been the subject of several articles resulting in some important and unexpected clarifications. Nevertheless, retracing the artist's career with precision continues to be an arduous task. His early maturity, during the 1350s, is particularly obscure. The present article focuses on that elusive decade, which is re-examined in the light of the attribution to the painter of a 'Saint Agnes' and a 'Martyr saint', presented here for the first time and identified as the side panels of a polyptych whose original central panel was the 'Crucifixion' conserved in the Ursuline church of Fribourg (Switzerland). The study of these paintings is part of a broader re-examination of Allegretto's artistic production, which, following his return from Tuscany – where his presence is documented in 1346 – shows traces of the influence of various artists active on the Florentine scene during those years.