"I've had cases where killers seemed to do even more improbable things than that."

The play that leads up to it is the improbable thing.

She seemed to glory in thinking up new and improbable things for them to do.

"With the force of his personality, he can make improbable things happen - at least to a certain degree."

That is certainly the most improbable thing that could have happened.

And of all the improbable things, I found myself holding his back.

She said so and was promptly reminded that they'd done far more improbable things in their tenure.

Much of the time, Macy's characters say and do the most improbable things.

If two improbable things happen simultaneously, they must be related.

It would also be likely to roll if I took the action you recommend and this improbable thing didn't happen.