Lyric discussion by Serenadier 

Pretty self-explanatory, a girl came into his life, and when she left, he is 'in the dark' (a metaphor for being lost), and he's telling us that 'if we see her, shine a light on her', which is telling us that we should help him find her back.

Pretty awkward coming from a Taio Cruz feature, but the song is really lovable.

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