Nitrogen revives: Cyclic N‐acyliminium ions were generated from α,β‐unsaturated γ‐lactams (1) and underwent intermolecular addition by indole nucleophiles (2) under the catalysis of a chiral Brønsted acid (3). A variety of N‐functionalizedindole derivatives containing a pyrrolidinone moiety (4) were assembled with high enantioselectivity. Bn=benzyl.