Young Writers Society

I am writing a story-thing where four people have to storm a castle. Only one of them is a legal adult, and the youngest is twelve. So if you have any ideas...
The castle is a normal medieval castle, the type you normally see in movies.
Any help would be very appreciated. I'm stuck.

By the way, they have to do it secretly because the people inside the castle are not superstitious and have magical powers.

Well, first off, that many people are not going to be 'storming' a castle, especially if only one of them is an adult. Storming involves taking something by force. What you are going to want to do if you want this to be realistic is to have them sneak in somehow.

During droughts, the moats of castles were dry. This was a problem because the moat also doubled as the sewage system. All the human waste and stuff went into them. So, they hired this guy called a 'gong farmer' to go around and pick up all the human waste from the moat. Now, there is a chance that your group could use this to their advantage. They could offer to do the job for him one day, then climb up through the amply wide chutes that people relieved themselves down, and enter the castle that way. It would be almost entirely unexpected, and therefore would catch some people by surprise. Especially if they could find the chute that went up to the quarters of whoever owns the castle. Then they could get in there and hold him hostage or something.

That's only one way though.

Another option is to just use the front door - come up with disguises and/or legitimate reasons to enter the castle. Terry Pratchett's characters in Monstrous Regiment dressed up as washerwomen, iirc. Your characters could pretend to be taking an injured friend to see the castle physician. Or they could pretend to be jesters or troubadours wanting to play for the local lord's entertainment. Or get some soldiers drunk, take their armour and uniform and go in dressed as them. Or something else.

Don't forget scouting. Highly, highly important step. If you don't know the castle and its defences, then you're dead in the water. Scouting methods can vary, depending on the practices of the time and customs of the world. For example, in Japan, it's considered dishonourable not to help an injured/sick person by the castle gates. Ninjas would take advantage of this all the time to scout the inside of a castle. They'd fake sick, get carried in, keep note of everything as they're being taken care of (maybe asking to go for a walk on the grounds, you never know) and vanishing. They'd then enter the castle later.

Speaking of, I'd suggest looking up ninjutsu techniques. They were the masters of breaking in and getting the job done.

Pretending to have business there, or pretending to be sick would not work. For one, they would not tend a sick person (unless there was something to get out of it) , because they are evil. It also would not work because they are fugitives and these people are on the lookout for them. They look distinctly different from the other people there.
Does anybody have any idea how big the toilet-things were in castles? I can't figure it out, and I can't find anything on it.
Thank you anyway for your suggestions, they might end up being helpful. Any other ideas?
Thank you!