  We present a Lagrangian describing a massive charged spin-2 field and a
scalar in a constant electromagnetic background, and we provide a consistent
description of the system. The Lagrangian, derived from string field theory
through a suitable dimensional reduction, propagates the correct number of
degrees of freedom within the light cone in any space-time dimension less than
26. We briefly discuss the higher-spin generalization of this construction,
that cures the pathologies of a massive charged particle of arbitrary integer
spin by introducing only finitely many new massive degrees of freedom.
