新たな証拠が見つかり、事態は急転した。
New evidence was found, and the situation took a sudden turn.
交渉は最終日に急転し、合意に至った。
The negotiations took an abrupt turn on the final day and reached an agreement.
病状の急転に家族は動揺を隠せなかった。
The family could not hide their distress at the sudden change in his condition.