ストーリーの展開が早い

develop/move/progress quickly

The story develops/moves quickly.

This drama progresses really fast.

展開が早いのでずっと見ていても飽きない

I never get tired/bored of watching the movie that develops very fast.

story development

The story development is so fast.

plot change

plot 物語の筋

The plot change is so quickly.

The plot changes very fast.

The plot is developing fast.

ストーリーのどんでん返し

Plot Twist!

fast/slow development/progression

The story is the slow development.

fast story development

I was surprised by the fast story development.

a sudden development in the story/situation.

There was a sudden development in the situation.

話の急展開