cut (one) off at the pass
To keep one from doing something (that usually involves an escape). Jeremy has been acting suspicious, so he's probably going to try to sneak out tonight, but I'm going to cut him off at the pass.
cut someone off at the pass
Fig. to block someone's effort to get away; to thwart someone's efforts. They are ahead now, but we'll cut them off at the pass. Try to cut off the bandits at the pass!