  We develop an inverse scattering transform formalism for the "good"
Boussinesq equation on the line. Assuming that the solution exists, we show
that it can be expressed in terms of the solution of a $3 \times 3$ matrix
Riemann-Hilbert problem. The Riemann-Hilbert problem is formulated in terms of
two reflection coefficients whose definitions involve only the initial data,
and it has a form which makes it suitable for the evaluation of long-time
asymptotics via Deift-Zhou steepest descent arguments.
