  We present a scenario where an axion-like field drives inflation until a
potential barrier, which keeps a waterfall field at the origin, disappears and
a waterfall transition occurs. Such a barrier separates the scale of inflation
from that of the waterfall transition. We find the observed spectrum of the
cosmic microwave background indicates that the decay constant of the inflaton
is well below the Planck scale, with the inflationary Hubble parameter spanning
a wide range. Further, our model involves dark matter candidates including the
inflaton itself. Also, for a complex waterfall field, we can determine
cosmologically the Peccei-Quinn scale associated with the strong CP problem.
