Accelerated aliens, the Scalosians, take over the ship by moving too fast to see.
Responding to a distress call, the Enterprise investigates the planet Scalos, and soon an odd buzzing is heard aboard the ship. Kirk is drugged by Scalosians, who live at a speed so accelerated that the crew appears frozen to them. The Scalosians want to take the crew as partners for their dying race.
The story uses the concept of accelerated time and is a clever sci-fi puzzle. It shows Kirk in action as he works with Spock to use a device to reverse the effect. Fans recall the buzzing noise and the unusual perspective of the crew trying to interact with the invisible enemies.