MacGyver faces off with a cunning new adversary whose carefully crafted plans put Mac at the epicenter of an impossible choice: save the life of a friend, or save the lives of hundreds of innocents. Also, Mac receives new information that will drive a wedge between him and his father.

After Oversight is almost killed in a bombing, he recruits Mac to help him find the suspected bomber, Mason. However, when Mason reveals he didn’t plant the bomb, the three team up to track down Codex, the shadow organization that set them up. Also, Mac meets his aunt Gwendolyn.

Mac's meeting with Desi's parents goes sideways when her brother finds himself in trouble and desperately needs their help. Also, Russ and Matty must ask an old nemesis for assistance when their new recruitment candidate is kidnapped.