Discovery of beta Cep pulsations in the eclipsing binary V453 Cygni

V453 Cyg is an eclipsing binary containing 14 and 11 M-circle dot stars in an eccentric short-period orbit. We have discovered beta Cep-type pulsations in this system using Transiting Exoplanet Survey Satellite data. We identify seven significant pulsation frequencies, between 2.37 and 10.51 d(-1), in the primary star. These include six frequencies that are separated by yet significantly offset from harmonics of the orbital frequency, indicating they are tidally perturbed modes. We have determined the physical properties of the system to high precision: V453 CygA is the first beta Cep pulsator with a precise mass measurement. The system is a vital tracer of the physical processes that govern the evolution of massive single and binary stars.