The phrase "a deadly turn" is correct and usable in written English.
It can be used to describe a situation that has taken a dangerous or fatal change, often in a narrative or dramatic context.
Example: "The investigation took a deadly turn when new evidence revealed the involvement of a notorious criminal."
Alternatives: "a fatal twist" or "a lethal shift".
That took a deadly turn, and highly public one, when a Chechen whistle-blower was killed here last year.
7 P.M. (Showtime 2) TRANSSIBERIAN (2008) Woody Harrelson and Emily Mortimer, right, star as Americans on a Moscow-bound train whose journey through Russia takes a deadly turn.
9 P.M. (Showtime 2) TRANSSIBERIAN (2008) Woody Harrelson, left, and Emily Mortimer play Americans on a Moscow-bound train whose journey through Russia takes a deadly turn.
11 45 A.M. (Encore) TRANSSIBERIAN (2008) Woody Harrelson and Emily Mortimer play Americans on a Moscow-bound train whose journey through Russia takes a deadly turn.
In this premiere episode Mr. James asks his crew to help him refurbish a classic Model A Ford roadster, but he refuses to disclose who the client is. 10 P.M. (Showtime 2) TRANSSIBERIAN (2008) Woody Harrelson and Emily Mortimer play Americans on a Moscow-bound train whose journey through Russia takes a deadly turn.
The demonstrations took a deadly turn in recent weeks, with at least 17 dead and about 150 injured.
Al Qaeda's affiliate in North Africa has carried out a string of killings, bombings and kidnappings against Westerners and African security forces in recent months that have raised fears that the Algerian-based group may be taking a deadlier turn.
WASHINGTON — Al Qaeda's affiliate in North Africa has carried out a string of killings, bombings and other lethal attacks against Westerners and African security forces in recent weeks that have raised fears that the terrorist group may be taking a deadlier turn.
Suddenly, no one wanted to risk my making a deadly right turn.
Commandos infiltrate a research facility after a deadly virus turns the entire staff into ravenous zombies.
The fighting represented the deadliest turn yet in a Sunni-led protest movement against the government of Prime Minister Nuri Kamal al-Maliki.
