This is a strange sentence
It's a follow up to 'Katten placerer musen i mælken'
My thoughts exactly!
The mouse lies white in the milk tonight...
No, but seriously, it probably means that it's dead.
Might be a reference to a song by gnags. "To små mus, i en spand med mælk, de svømmede rundt, så godt de ku'.".
it shouldn't be "Musen ligger nu i mælken"?