to lie in wait (for); to be on the watch (for); to wait (for); to watch (for)
出口で待ち構えていた。
They were lying in wait at the exit.
待ち構えた猫が鳥に飛びかかった。
The cat that had been lying in wait pounced on the bird.
何が待ち構えるか誰にも分からなかった。
No one knew what awaited.