In the title compound, C(11)H(8)BrNO(2), the nine-membered fused-ring is nearly planar [maximum deviation = 0.022 (2) Å] and the allyl group is arched over the nine-membered fused-ring at a dihedral angle of 89.2 (1)°. Weak inter-molecular C-H⋯O hydrogen bonding is present in the crystal structure.