This paper examines the dynamics of the gravitational slingshot, wherein the trajectory of a space probe moving at initial speed v o with impact parameter b toward a planet of mass M is deflected through some scattering angle φ. Expressions for the probe's trajectory, scattering angle, characteristic flyby time, and maximum linear and angular speeds are developed at a level appropriate to that of an advanced-undergraduate mechanics student familiar with the general integrals of central-force motions; no assumption is required as to the hyperbolic nature of the trajectory. It is emphasized that the dimensionless parameter $varepsilon = {{bv_o^2 } mathord{left/ {vphantom {{bv_o^2 } {GM}}}
ight. kern-1.2pt} {GM}}$ characterizes much of the dynamics of this problem.