The Federation calls on Adm. James T. Kirk (William Shatner) and the crew of the Starship Enterprise to contain an immense nimbused object that's on a crash course with Earth. After investigating, the crew discovers that the alien cloud harbors artificial intelligence with an ominous primary directive. Crisis strikes when a probe dispatched by the energy cloud attacks the crew, abducting navigator Lt. Ilia (Persis Khambatta). An android look-alike containing her memories shows up soon after.