Recently three-dimensional versions of honeycomb-lattice iridates, beta and gamma phases of Li2IrO3, have been discovered. It has been theoretically suggested that these hyperhoneycomb iridates may hold promise for the realization of the Kitaev spin liquid or the exactly solvable model for the elusive quantum spin liquid phase. Recent scattering experiments on these systems have, however, revealed highly non-trivial magnetic spiral phases. We propose a theory that may explain the emergence of this unusual magnetic order and discuss why the current experimental data may suggest that the hyperhoneycomb iridates are not too far from the Kitaev limit.