  V453 Cyg is an eclipsing binary containing 14 Msun and 11 Msun stars in an
eccentric short-period orbit. We have discovered $\beta$ Cep-type pulsations in
this system using TESS data. We identify seven significant pulsation
frequencies, between 2.37 and 10.51 d$^{-1}$, in the primary star. These
include six frequencies which 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 Cyg A 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.
