Read the following excerpt from a story:
'The old lighthouse stood on the cliff's edge, a solitary guardian against the churning sea.
For years, its beam had cut through the thickest fog, a steadfast promise to sailors.
But now, its light was gone, and the townspeople spoke in hushed tones of the darkness that had fallen.
Liam, however, whose grandfather had been the last keeper, refused to believe the light was gone for good.
He spent his days poring over old nautical charts and his grandfather's journals, searching for a clue, a forgotten switch, anything to reignite the beacon.'
Which of the following sentences best describes the theme of the excerpt?
