Zhè bù diànyǐng jiǎng de shì yī gè zhíyè shāshǒu de gùshi.
This movie is about a professional hitman.
Tips
usage
杀手 can mean a literal killer/assassin, but is also used figuratively as 'killer app/feature' (杀手锏 shāshǒujiǎn) or as a metaphor for something devastating, like 健康杀手 (health killer).