The phrase "nefarious plans" refers to wicked or evil intentions or schemes. It suggests someone has intentions to do something very bad or harmful. Full definition
Must admit, I am really glad for Google coming in to disrupt Apple / Jobs» nefarious plans of dominating mobile computing. (gigaom.com)
The mid-credits scene showed us that the story was nowhere near over, that Cybertronian sorceress Quintessa was still alive and had more nefarious plans for Earth. (cbr.com)
A vacationing or road - tripping couple that fall prey to crazed locals with nefarious plans is well trodden at this point. (bloody-disgusting.com)