D.C. Code § 18-308

Unless a different disposition is made or required by the will, if a devisee or legatee dies before the testator, leaving issue who survive the testator, the issue shall take the estate devised or bequeathed as the devisee or legatee would have done if he had survived the testator. Unless a contrary intention appears by the will, the property comprised in a devise or bequest in a will that fails or is void or is otherwise incapable of taking effect, shall be deemed included in the residuary devise or bequest, if any, contained in the will.