I want you to let me know at the first sign of trouble.

"Were you sent here to leave at the first sign of trouble?"

At the first sign of trouble, you run for the river.

And now, at the first sign of trouble, he was taking off.

Just saying yes may be the first sign of trouble.

At the first sign of trouble, they would be brought inside.

He knew there had not been any positive sign of trouble.

I should have come running to you at the first sign of trouble.

No sign of trouble that she could see or hear.

The first sign of trouble came before she had even moved in.