  We show that a plane continuum X is indecomposable iff X has a sequence (U_n)
of not necessarily distinct complementary domains satisfying what we call the
double-pass condition: If one draws an open arc A_n in each U_n whose ends
limit into the boundary of U_n, one can choose components of U_n minus A_n
whose boundaries intersected with the continuum (which we call shadows)
converge to the continuum.
