Extremal transition is a certain kind of contract-deform surgery, which plays a key role in the classification of Calabi-Yau 3-folds. The study of how Gromov-Witten invariants change under this surgery, pioneered by A. Li and Y. Ruan, has been a long-standing goal in mirror symmetry. In this talk, I will present a local model of cubic extremal transition and then propose a new correspondence in terms of quantum D-module. We will show that the quantum D-module of one side may be recovered, up to gauge equivalence and analytic continuation, as a limit of the quantum D-module of the other side when restricted to certain monodromy invariant subspace. The first hour will be devoted to background and a historical account of this problem. In the second hour, I will explain some ideas involved in the proof. This is a report on my work in progress. Speaker(s): Rongxiao Mi (UM)