Exactly how any such plan would work is far from certain.
If his plan had worked, we three would be dead.
He knew his own plan had worked well in the past.
No one knows for certain if the plan will work.
At least long enough to see if the plan works.
The plan works, and she gets to keep her job.
Her plan would work if she knew anything at all of human nature.
His plan might have worked if I hadn't killed him.
If I could do that, then my plan would work.
Some saw no hard evidence that such a plan could work.