  We present the discovery of a unique object, a chemically peculiar Ap-type
star showing $\delta$ Scuti pulsations which is bound in an eclipsing binary
system with an orbital period shorter than 3 days. HD 99458 is, therefore, a
complex astrophysical laboratory opening doors for studying various, often
contradictory, physical phenomena at the same time. It is the first Ap star
ever discovered in an eclipsing binary. The orbital period of 2.722 days is the
second shortest among all known chemically peculiar (CP2) binary stars.
Pulsations of $\delta$ Scuti type are also extremely rare among CP2 stars and
no unambiguously proven candidate has been reported. HD 99458 was formerly
thought to be a star hosting an exoplanet, but we definitely reject this
hypothesis by using photometric observations from the K2 mission and new radial
velocity measurements. The companion is a low-mass red dwarf star
($M_{2}=0.45(2)$ M$_{\odot}$) on an inclined orbit ($i=73.2(6)$ degrees) that
shows only grazing eclipses. The rotation and orbital periods are synchronized,
while the rotation and orbital axes are misaligned. HD 99458 is an interesting
system deserving of more intense investigations.
