  We construct a family of five-dimensional gauged supergravity actions which
describe flop transitions of M-theory compactified on Calabi-Yau threefolds.
While the vector multiplet sector can be treated exactly, we use the Wolf
spaces X(1+N) = U(1+N,2)/(U(1+N) x U(2)) to model the universal hypermultiplet
together with N charged hypermultiplets corresponding to winding states of the
M2-brane. The metric, the Killing vectors and the moment maps of these spaces
are obtained explicitly by using the superconformal quotient construction of
quaternion-Kahler manifolds. The inclusion of the extra hypermultiplets gives
rise to a non-trivial scalar potential which is uniquely fixed by M-theory
physics.
