  We present a complex study of the eclipsing binary system, AB Cas. The
analysis of the whole TESS light curve, corrected for the binary effects,
reveals 112 significant frequency peaks with 17 independent signals. The
dominant frequency $f_1 = $17.1564 d$^{-1}$ is a radial fundamental mode. The
$O-C$ analysis of the times of light minima from over 92 years leads to a
conclusion that due to the ongoing mass transfer the system exhibits a change
of the orbital period at a rate of 0.03 s per year. In order to find
evolutionary models describing the current stage of AB Cas, we perform binary
evolution computations. Our results show the AB Cas system as a product of the
rapid non-conservative mass transfer with about 5-26 % of transferred mass lost
from the system. This process heavily affected the orbital characteristics of
this binary and its components in the past. In fact, this system closely
resembles the formation scenarios of EL CVn type binaries. For the first time,
we demonstrate the effect of binary evolution on radial pulsations and
determine the lines of constant frequency on the HR diagram. From the binary
and seismic modelling, we obtain constraints on various parameters. In
particular, we constrain the overshooting parameter, $f_{\rm ov}\in
[0.010,~0.018]$, the mixing-length parameter, $\alpha_{\rm MLT}\in[1.2,~1.5]$
and the age, $t \in [2.3,~3.4]$ Gyr.
