I`m looking for a movie, i assume was in the 90`s, but i don`t remember much about it.?

okay, so i remember when i was little, i watched these movies, yes they were kinda a series. i`m thinking the name had something to do with a treehouse and a club ``the treehouse club`` or something along those lines. i remember one movie 3 boys and one girl (kids) went to find treasure, and ended up finding a heart on a brick wall which was a clue, and that`s all i remember, your help would be greatly appreciated (: thanks