Looking over the box and its bindings, there doesn't seem to be an easy way to open it. With as eerie as the situation is, you're not even sure you want to, so you turn to walk back to your friends. As you move away, you feel something catch your sleeve. You turn back and look, but there's nothing there. There's nothing near your sleeve at all.
You're pondering this when you hear a sound from the crate. It's a small sound, barely more than a sigh, but clearly a whisper. It says, "Free me." You freeze in place. Should you reply? Should you try the box again? Neither of those sound right, so you turn to leave again. This time, you feel something grab your whole arm. Again, you look, but of course there's nothing.
"Don't leave," comes that tiny whisper again. "Free me." This time, when you turn to leave, you break into a run. This time, the thing that catches you does so by your head, pulling you down, pounding you into the cement floor.