In the title compound, C17H15NO2S, the two C atoms linking the S and carbonyl C atoms of the seven-membered thiazepine ring are disordered over two sites, with occupancies of 0.511 (4) and 0.489 (4); both disorder components adopt distorted twist-boat conformations. In the crystal, N—H...O and C—H...O hydrogen bonds link inverted-related molecules into dimers, incorporating R12(6) and R22(8) ring motifs; the acceptor carbonyl O atom is bifurcated. These dimers are further linked by C—H...O hydrogen bonds, forming supramolecular tapes running along the a axis.