Thanks for such a clear differentiation between the Hook and the Lock. I'm sure there can be (and is) much debate about the particulars of each for a given story. But this gives us beginners something to chew on as we create our stories (even if it's a novel, instead of a screenplay).

I think there's two questions in this one.

1) How big should the (major) plot point in Act One be?

2) Where should it go?

The major plot point in the first Act MUST be big enough to propel the entire movie for at least 90 pages. This plot point is often referred to as the Inciting Incident. That's really the only requirement.

Where it goes in the first act is more debatable. Most Classical Hollywood structure puts it somewhere between 15-25. BACK TO THE FUTURE it's Marty's jump to the past. BURIED, it's on page 1 when Paul Conroy wakes up and he's buried alive.

Here's what's important -- as a reader, don't you know what has to be accomplished for the story to end once those plot points are presented?

Marty needs to get back to the future. Paul needs to get out of this coffin.

I call it simply the "Oh, shit!" moment. And that should be your audience's reaction.

Look at the examples Scott cites above. All of them are "Oh, shit!" moments.

Here's another:

Luke rushes home, only to find his aunt and uncle horribly murdered, their remains smoldering. "Oh, shit!"

hey scott, just reading this now. thanks for your insights- very helpful.