Let $G=(V,E)$ be an arbitrary undirected source graph to be embedded in a target graph $EM$, the extended grid with vertices on integer grid points and edges to nearest and next-nearest neighbours. We present an algorithm showing how to embed $G$ into $EM$ in both time and space $O(|V|^2)$ using the new notions of islands and bridges. An island is a connected subgraph in the target graph which is mapped from exactly one vertex in the source graph while a bridge is an edge between two islands which is mapped from exactly one edge in the source graph. This work is motivated by real industrial applications in the field of quantum computing and a need to efficiently embed source graphs in the extended grid.