"The greatest love story ever filmed" is the modest encomium reserved by MGM for its latest romantic outburst. David Niven and Teresa Wright are the protagonists in this cosmic match, and they are backed up by a talking house, a war, and 60-odd years worth of flashbacks.

It all begins when Niven's father brings a newly-orphaned girl named Lark into the house. Niven, aged five, takes an immediate liking to her, but his sister--who distinguishes herself as a real five-star nogoodnick throughout--feels otherwise, and manages to make the two of them acutely unhappy for twenty years, at the end of which time they fall violently in love, reveal their burning passions to each other, but part forever due to a clever bit of trickery on the part of the sister.

This is all mixed with a modern girl, the niece of the now-senile Niven, who comes to stay in the house, in 1940 and meets a young flyer. They, too, are in love but manage to hide it from each other until almost too late. The elderly uncle observes all this with disquiet, and divides his time between hearing the voice of the non-dead Lark and advising the girl to get off the dime and marry the guy.

The whole situation is saved by the happy advent of a Heinkel bomber, which blows up the house, kills the old man, lays Lark's ghost, and throws the two current lovers violently together. This leaves everybody happy but the customers.