“The Doomsday Machine,” Suspense, and Dodging the Sagging Middle

Have you ever been watching a movie or reading a novel, and somewhere in the middle (aka Act 2), it bogs down? If Act 2 is sluggish enough, you’ve even lost interest in the outcome, Act 3.

Here’s what probably happened. The writer was up against a deadline and threw all manner of challenges at the characters in that midsection to perk up the action and avoid what’s known as “the sagging middle.” But ironically, the wrong kind of action can drag at the momentum.

The challenges faced by characters in the middle of a movie or novel must be more than a random series of obstacles for those characters to overcome. They must mean something to the characters’ goals. And the challenges must also relate intimately to the pending crisis.

Setup for successful Act 2 suspense
“The Doomsday Machine,” my favorite episode of classic “Star Trek,” is full of driving suspense. Some of the most memorable tension in the episode is found in the very middle, making this middle anything but saggy. Let’s see how the writer did it.


In Act 1 of “The Doomsday Machine,” the starship “Enterprise” encounters a sister ship, the “Constellation,” that’s adrift and all-but-demolished after battling a giant robot—a Doomsday Machine—that eats planets. Out of a crew of more than 400, only the commander of the “Constellation,” Matt Decker, has survived. The robot, impervious to phaser weapons from the “Constellation,” has continued on a course that will allow it to eat its way through the heart of the Milky Way galaxy. So “Enterprise” Captain Jim Kirk, temporarily aboard the “Constellation,” decides that his ship will take the broken vessel in tow and proceed to the nearest star base so they can warn Command about the threat. He sends Decker back to the “Enterprise” for medical treatment, and he and a repair team remain aboard the “Constellation” to restore minimal mobility to the starship and prepare it for tow.

Doomsday machine

That brings us to the middle of the episode. Act 2. At this point, the Doomsday Machine robot circles back into the vicinity and attacks the “Enterprise.” Decker, grieving the loss of his crew and making decisions while in the grip of post-traumatic stress disorder, assumes command of the “Enterprise.” Kirk, stranded aboard the “Constellation,” watches his ship get beat up by the robot.

The look and feel of a successful Act 2
The core of this episode’s Act 2 action plays out in the following five-minute YouTube clip. (Caveat: 1960s-style special effects ahead.) Watch how the suspense leaps back and forth between Decker on the “Enterprise” and Kirk on the “Constellation.”

And this isn’t even the climax of the episode.

Key points of Act 2
Matt DeckerDecker’s decisions at 0:07, 0:30, 1:47, and 1:56 are wrong. His credibility as a starship commander is gone. On some level, he realizes that phaser weapons from the “Enterprise,” like those from the “Constellation,” won’t stop the robot, but he’s unable to think logically. He uses the ineffective strategy of phaser barrage as a surrogate for beating on the robot with his fists. The result? The robot damages the “Enterprise” and threatens the lives of Kirk’s crew. Even though we can see this coming, it’s still suspenseful.

Jim Kirk

Aboard the crippled “Constellation,” the usually-cool and often-correct Captain Kirk engages in a short-sighted act of desperation (at 1:00, 4:06, and 4:23) to draw the robot off the “Enterprise.” His act pays off for the “Enterprise.” But Kirk has made a whopper of a mistake. Fixated on saving the “Enterprise,” he imperils himself and his crew members aboard the “Constellation.” Kirk’s “Oh-sh*t!” expression at 4:40 says it all.

What else do you see that gives this sequence tension?

What this writer did well
Many have commented that the unique musical score written for “The Doomsday Machine” contributes to the atmosphere. Yes, it does, but even without music, this sequence would be suspenseful. Writer Norman Spinrad exploited the fears of Decker and Kirk, developing tension organically from personality weaknesses in both characters. Then he milked the resulting suspense in a crisis that gives viewers a taste of death.

Act 2, written well, is supposed to guide you into Act 3. Everything that happens in Act 2 of “The Doomsday Machine” sets the stage for even greater challenges in Act 3, the climax of the episode, and makes you eager to find out how the dilemma gets resolved.

Sagging midsections in movies and novels may contain random, meaningless obstacles like a car chase, explosions, a seduction, or a gunfight. Hidden behind those are opportunities the writer missed to craft suspenseful challenges that arose due to character weaknesses.

Can you name a movie or novel with a midsection that didn’t hold your attention?


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