When patroller Hurst falls into a whispering portal, Gatekeepers Pippin and Tilly go after him, but are caught in crisscrossing times. Pippin sends out a desperate message for help, which is picked up by Ruarc on a distant world, familiar with timetwists and portals. Pippin and Ruarc manipulate time and events, sometimes with humor, sometimes with miscalculations, until even Ruarc gets lost in the temporal knots. They must find their missing patroller, stop the use of handheld portal devices, and return home before they're lost in the timetwists, while they evade and try to stop the avaricious and murderous group who tries to manipulate all portal devices. Tangling the branches of time.