I am the sort of writer who plots his projects out ahead of time and when I do that plotting I like to have a structure for the story. Most of the time I use a three-Act system of Establishment, Conflict, Resolution, but lately I have been experimenting with five acts. One way to digest and understand an act structure, particularly if you intend to use it for your own work, is to look at something already in existence and see how the structure fits on that. This is not to say that the screenplay writers for Alien used a 5 act system, they most likely used a 3 act method, but nearly any story can be broken down by either method.

ACT I Establishment

In the first act of a 5 act story not only are characters and conflicts established in the first act, but themes and the nature of the world is laid out for the audience/reader. In Alien I would suggest that the first act goes from the film start, naturally, and concludes with the decision to land on the planet/moon about Zeta-2 Reticuli. Quite a bit is covered in this passage. We learn our heroes are working class people, not space explorers as in other films of the genre, we learn that they don’t get along, and that they are deeply concerned with money. The ‘Company’ unnamed in the original, is a source of threat and power that exists in almost omnipotent state off screen.

ACT II Complications

Here things go wrong and the characters are tested with a series of setbacks. The setbacks are dangerous and threatening to the order of the world, but not yet irreversible.

The Landing goes badly, damaging the ship. The trip to the source of the signal that they have been forced to investigate – at this point the nature of ‘force’ appears to be solely the threat of money being withheld, is difficult and the first translation hint that the signal is not a distress call but a warning. Cain is ridden by the creature and interpersonal tensions flare. While attempts to remove the creature from Cain fail, the ship is repaired and the crew leaves the planet for home.

ACT III Crisis

In Act three, classically called the Climax though today we tend to use that for resolution, there is a fundamental change that is irreversible, MacBeth has Banquo murder for example. There is a clear turning point in the plot that takes place in Act 3 from which the character become trapped in their choices and must face the consequences that their fates hold.

Cain appears to recovery from the alien parasite but shortly dies in a horrific manner. Now the crew find themselves trapped on a ship with a deadly creature and increasingly dangerous attempts to deal with it result in further loss of life.

ACT IV Resolution

With a 3 act structure it is usual to think of resolution as the ending, how everything turned out in the end, but with a five act structure this also includes the final reveals and plot twists that lead to the Hero’s victory or failure in their plot. Act 4 for Alien is Ripley’s act, it is where she is revealed to be the actual hero of the story and takes charge to deal with the creature. Act 4 also reveals Ash to be the turncoat and company man working against their interests. With all the important elements in place and revealed the hero, Ripley, drive to the solution, here destroying the ship with the creature aboard.

ACT V Denouement

In my opinion Act V for Alien is everything on the shuttle after Ripley launches from the ship. It is the final confrontation between the hero and villain, this case a monster, but nothing new is added. All the elements, including the plan to ‘blow it out the airlock’ have already been established and are in place. The final obstacle is faced and the hero either overcomes and grows from the experience or fails due to their tragic flaw, Of course in Alien Ripley overcomes and earns her ‘happy ending.’