  We report the discovery of a hot Jupiter candidate orbiting HS Psc, a K7
($\approx$0.7 $M_\odot$) member of the $\approx$130 Myr AB Doradus moving
group. Using radial velocities over 4 years from the Habitable-zone Planet
Finder spectrograph at the Hobby-Eberly Telescope, we find a periodic signal at
$P_b = 3.986_{-0.003}^{+0.044}$ d. A joint Keplerian and Gaussian process
stellar activity model fit to the RVs yields a minimum mass of $m_p \sin i =
1.5_{-0.4}^{+0.6}$ $M_\mathrm{Jup}$. The stellar rotation period is well
constrained by the Transiting Exoplanet Survey Satellite light curve
($P_\mathrm{rot} = 1.086 \pm 0.003$ d) and is not an integer harmonic nor alias
of the orbital period, supporting the planetary nature of the observed
periodicity. HS Psc b joins a small population of young, close-in giant giant
planet candidates with robust age and mass constraints and demonstrates that
giant planets can either migrate to their close-in orbital separations by 130
Myr or form $in \; situ$. Given its membership in a young moving group, HS Psc
represents an excellent target for follow-up observations to further
characterize this young hot Jupiter, refine its orbital properties, and search
for additional planets in the system.
