In the mid-21st century, the Kernel, a strange object on a five-hundred-year-orbit, is detected coming from high above the plane of the solar system. Could it be an alien artefact? In the middle of climate-change crises, there is no mood for space-exploration stunts - but Reid Malenfant, elderly, once a shuttle pilot and frustrated would-be asteroid miner, decides to go take a look anyway. Nothing more is heard of him. But his ex-wife, Emma Stoney, sets up a trust fund to search for him the next...