Thomas was held prisoner for almost one year in the family castles at Monte San Giovanni and Roccasecca in an attempt to prevent him from assuming the Dominican habit and to push him into renouncing his new aspiration.
Thomas ditawan selama hampir satu tahun dalam kastel-kastel keluarganya di Monte San Giovanni dan Roccasecca dalam upaya mencegahnya agar tidak mengambil jubah biara Dominikan dan mendesaknya agar meninggalkan aspirasi barunya.