The Flying Stars' is one of Chesterton's mysteries featuring Father Brown. It's actually the first of these short stories I've read and I picked it up more because it's a Christmas mystery than to meet Father Brown, even though he is a character I'd like to read more of.
The story takes place at an English manor home on Boxing Day. A young lady and the young man who lives next door are present, as is the girl's father, Colonel Adams, a newly arrived uncle and a quite rich godfather. Also present, in addition to the servants, simply because the Colonel likes his company is the local priest, Father Brown. The godfather has brought a gift for the young lady, a set of three gorgeous, large diamonds, which he has tucked away in his coat pocket.