Busted daughter about to sneak out

I just busted my 15 year old daughter about to sneak out of the house while she thought I was asleep. She said she was going to walk to a friends house, but not sure what to believe. Her friends have fairly relaxed parents that let them go to parties that they know is going to have alcohol and weed, but they aren't fussed. I know I can't wrap her in cotton wool and teenagers do crap like this, but it scares the crap out me. What if something happened while she was out? And I thought she was in bed the whole time? I've now locked her bedroom window with a key and taken her phone and laptop off her, but I am unsure on how to punish her. She is grounded of course, but is that enough? I want to get her away from her friends but I get scared that all of this will push a big wedge between us. via /r/Parenting http://ift.tt/2tBy10s