The chapter develops a theory of branching spatiotemporal histories that accommodates indeterminism and the insights of general relativity. A model of this theory can be viewed as a collection of overlapping histories, where histories are defined as maximal consistent subsets of the model’s base set. Subsequently, generalized (non-Hausdorff) manifolds are constructed on the theory’s models, and the manifold topology is introduced. The set of histories in a model turns out to be identical with the set of maximal subsets of the model’s base set with respect to being Hausdorff and downward closed (in the manifold topology). Further postulates ensure that the topology is connected, locally Euclidean, and satisfies the countable sub-cover condition.