No silly. The 2008
The Happening (not a remake) with Marky Mark and Zooey Deschanel and John Leguizamo.
SPOILER:
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Plants made people kill themselves and an indicator that the neurotoxin had infected a group was that they all started walking backwards before killing themselves in some gruesome manner.
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It's an M Night Shama-lama-ding-dong movie.