Roisin and François first meet in the snowy white expanse of Antarctica. And everything changes. While Roisin grew up in a tiny village in Ireland, ablaze with a passion for science and the skies and for all there is to discover about the world, François was raised by his beautiful young mother, who dreamt of new worlds but was unable to turn her back on her past. As we loop back through their lives, glimpsing each of them only when a comet is visible in the skies above, we see how their paths cross as they come closer and closer to this moment. Theirs are lives filled with love and hope and heartbreak, in a story that shows how strangers can be connected and ghosts can be real, and the world can be as lonely or as beautiful as the comets themselves.