The phrase "hatch a plot" refers to the act of scheming, planning or devising a cunning or nefarious plan. There are several alternative phrases that can be used to convey the same meaning. For example, one could say "concoct a scheme," "cook up a plan," "devise a plot," or "formulate a strategy." Other phrases might include "scheme and plot," "plot and plan," "plot and connive," or "harbor a dark design." Regardless of the wording used, the intention behind the phrase remains the same: to suggest a person or group is working behind the scenes to achieve a specific goal, often through underhanded or secretive means.