I agree with all the comments regarding placing chocolates away from your dogs reach. But here's the thing a dog is a dog and he or she will sniff out what ever it is you've hidden!
I have a 3 year old boxer bitch, and she ate a whole 2kg, 85% dark chocolate easter egg, and truffles (in plastic bag inside) and all the wrappings on the outside! when she was less than 6 months old, and i thought that by putting it in a closed kitchen cupboard I'd be safe!
I spent all of that Easter Sunday evening mopping chocolate vomit & worse, and stayed up all night giving her water drop by drop to keep her hydrated.

I called the vet immediately when I found out what had happened, and he called the poison unit then called me back and told me she'd had 3 x the lethal dose!! He told me to give her plenty of water, but avoid letting her gulp it down and he needed to see her in the morning.

When i took her in the next day, it was as if nothing had happened! I was totally shattered with match sticks jammed in my eyes and she was leaping & bounding about the surgery like any boxer puppy should. To say he was astonished is an understatement, and to say I was relieved is an even bigger understatement.

We don't do Easter in our house anymore! because it's just not worth the risk. But don't panic if your dog does eat chocolate, it does depend on the dogs themselves as to how they react, but it isn't always fatal. tell the vet immediately how much and what kind of chocolate and they'll be in a better position to help you.
Phil