V453 Cyg is an eclipsing binary containing 14 { M } _ { \odot } and 11 { M } _ { \odot } 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 .