Crying over spilt milk won't bring your son back. In fact the only thing that will bring him back is to come to the following address tomorrow at Midnight.
Deep within the Parisian Catacombs, in a secret chamber long since sealed, your son awaits you. Paris is beautiful this time of year, and your son misses you tremendously. He cries every night.
I would suggest map reading, as the catacombs are vast and confusing.
A finely trained canine might be able to sniff out your boy's scent, but I wouldn't count on it. The catacombs are cold, dank, and oh so full of secrets.
Oh wait, sorry, this one's for me. BWAHAHAHAHA! Wow! that really works! I feel great!
Calling the cops would be useless. By the time they arrived, your precious Aidan will have already met with a fate most...unsavory.
How else are you going to be able to afford the two million dollar ransom I demanded?
All of the clues to your son's location are hidden within the Parisian National Archives. If you can solve my riddles, you might just get to hold your darling boy in your arms once more.
This is just generally good advice. Exercise is very important, especially as you get older. But also you will need to do a lot of walking as you descend into the hellish bowels of Paris' infamous grave tunnels. I strongly recommend bringing a camelback or nalgene.
Sorry, this one's also for me. Isn't that right... Aidan?