Helm had only to follow the debris to its source.

Her eyes slowly followed the thin streak of light to its source.

Curiosity and loneliness moved her to follow the sound to its source.

She felt an irresistible need to follow them to their source.

Now they were following the trail to its source, two million years later.

Determined to follow the sounds to their source, he started down the corridor?

Instead, I have followed them to their source, this canyon.

Then he turned around and followed the voices to their source.

This time, he followed the call to its source.

The noise was coming from there, and he followed it to its source with his eyes.