  Putting a twisted version of N=4 super Yang-Mills on a curved
four-dimensional manifold generically breaks all conformal supersymmetries. In
the special case where the four-manifold is a cone, we show that exactly two
conformal supercharges remain unbroken. We construct an off-shell formulation
of the theory such that the two unbroken conformal supercharges combine into a
family of topological charges parameterized by CP^1. The resulting theory is
topological in the sense that it is independent of the metric on the
three-dimensional base of the cone.
