A plan was forming in his head, and she wasn't part of it.

I asked him, for a plan had been slowly forming in my mind.

Was it at this point that his plan had formed?

As he moved, a plan was already forming in his mind.

And this plan has been forming in his mind for a very long time.

The plan of the crime formed itself in your head.

A new and more important plan was forming in his brain.

So far, no clear plan had formed in his mind.

At the same time a plan was forming in her mind.

These plans would then form the basis for targeted financial and other support.