  Hot Jupiter systems provide unique observational constraints for migration
models in multiple systems and binaries. We report on the discovery of the
Kepler-424 (KOI-214) two-planet system, which consists of a transiting hot
Jupiter (Kepler-424b) in a 3.31-d orbit accompanied by a more massive outer
companion in an eccentric (e=0.3) 223-d orbit. The outer giant planet,
Kepler-424c, is not detected to transit the host star. The masses of both
planets and the orbital parameters for the second planet were determined using
precise radial velocity (RV) measurements from the Hobby-Eberly Telescope (HET)
and its High Resolution Spectrograph (HRS). In stark contrast to smaller
planets, hot Jupiters are predominantly found to be lacking any nearby
additional planets, the appear to be "lonely" (e.g. Steffen et al.~2012). This
might be a consequence of a highly dynamical past of these systems. The
Kepler-424 planetary system is a system with a hot Jupiter in a multiple
system, similar to upsilon Andromedae. We also present our results for
Kepler-422 (KOI-22), Kepler-77 (KOI-127; Gandolfi et al.~2013), Kepler-43
(KOI-135; Bonomo et al.~2012), and Kepler-423 (KOI-183). These results are
based on spectroscopic data collected with the Nordic Optical Telescope (NOT),
the Keck 1 telescope and HET. For all systems we rule out false positives based
on various follow-up observations, confirming the planetary nature of these
companions. We performed a comparison with planetary evolutionary models which
indicate that these five hot Jupiters have a heavy elements content between 20
and 120 M_Earth.
