  The dramatic hard-soft spectral transition in Black Hole Binaries is
important as it is associated with the collapse of the jet and with the
strongest low frequency QPOs. These transition spectra (intermediate and very
high state: VHS) are complex, with soft but distinctly non-thermal
Comptonisation which merges smoothly into the disc emission. Here we develop a
physical model for the accretion flow which can accommodate all these features,
with an outer standard disc, which can make a transition to an energetically
coupled disc-corona region, and make a further transition to a hot inner flow
which can be radiatively inefficient if required. The code explicitly uses
fully relativistic emissivity (Novikov-Thorne), and all Comptonisation is
calculated with a hybrid (thermal and non-thermal) electron distribution. We
fit this to a VHS spectrum from GX 339-4. We show that the complex continuum
curvature produced by a hybrid electron distribution is enough to remove the
strong constraint on black hole spin derived from reflection using simpler
Comptonisation models. More fundamentally, we show that the VHS cannot be fit
with the same Novikov-Thorne emissivity which can fit the disc dominated
spectrum but instead requires that the inner flow is somewhat radiatively
inefficient. This is consistent with an accretion powered jet, but simultaneous
radio data show that the jet has already collapsed at the time of our data.
Instead, it could point to truncation of the inner flow at radii larger than
the innermost stable circular orbit, as predicted by the Lense-Thirring QPO
models.
