A runaway monocycle (or, U.S., unicycle) creates pandemonium, then, under control, enables Mark to pull off a life-saving stunt. The chase affords a few laughs (the sentry who cries ""Who goes there, "" the stiff soldiers who topple in a row) but the finale--Mark riding the monocycle across a telegraph wire to a burning building--is not only impossible, it's also implausible in terms of Mark's ineptitude. Wobbly whimsey.