  We present a QCD analysis of the cumulative out-of-event-plane momentum
distribution in DIS process with emission of high p_t jets. We derive the
all-order resummed result to next-to-leading accuracy and estimate the leading
power correction. We aim at the same level of accuracy which, in e+e-
annihilation, seems to be sufficient for making predictions. As is typical of
multi-jet observables, the distribution depends on the geometry of the event
and the underlying colour structure. This result should provide a powerful
method to study QCD dynamics, in particular to constrain the parton
distribution functions, to measure the running coupling and to search for
genuine non-perturbative effects.
