Once a crab takes the bait, the line will tighten.

The lines at the corners of Vaughn's eyes tightened, as though he might have smiled.

He was still slouched back, but the line of his mouth had tightened.

I had fished for half an hour when I felt the line tighten.

Then the lines of his face tightened once more, alert intelligence and awareness flooded back.

I reeled up with a sigh, but the line tightened again.

The line tightened, and the deck tilted under the weight.

His voice was light, but Olive could see the worry lines in the old man's face tighten as he spoke.

The line tightened and went straight into the water.

Hesitation slowly became determined silence; the line of her mouth tightened.