coup de thé·â·tre 
(k′ də tā-ätrə)
(k′ də tā-ätrə)n. pl. coups de théâtre (k′)
1. A sudden dramatic turn of events in a play.
2. An unexpected and sensational event, especially one that reverses or negates a prevailing situation.
[French : coup, stroke + de, of + théâtre, theater.]