  Using proton-proton collision data collected by the LHCb experiment at
sqrt(s) = 7 TeV, corresponding to an integrated luminosity of 1.0 fb^{-1}, the
ratio of branching fractions of the B0 -> D*- pi+ pi- pi+ decay relative to the
B0 -> D*- pi+ decay is measured to be B(B0 -> D*- pi+ pi- pi+) / B(B0 -> D*-
pi+) = 2.64 \pm 0.04 (stat.) \pm 0.13 (syst.). The Cabibbo-suppressed decay B0
-> D*- K+ pi- pi+ is observed for the first time and the measured ratio of
branching fractions is B(B0 -> D*- K+ pi- pi+) / B(B0 -> D*- pi+ pi- pi+) =
(6.47 \pm 0.37 (stat.) \pm 0.35 (syst.)) x 10^{-2}. A search for orbital
excitations of charm mesons contributing to the B0 -> D*- pi+ pi- pi+ final
state is also performed, and the first observation of the B0 ->
Dbar_{1}(2420)^0 pi+ pi- decay is reported with the ratio of branching
fractions B(B0 -> (Dbar_{1}(2420)^0 -> D*- pi+) pi- pi+) / B(B0 -> D*- pi+ pi-
pi+) = (2.04 \pm 0.42 (stat.) \pm 0.22 (syst.)) x 10^{-2}, where the numerator
represents a product of the branching fractions B(B0 -> Dbar_{1}(2420)^0 pi-
pi+) and B(Dbar_{1}(2420)^0 -> D*- pi+).
