An Adventure in Porto

The twins, and their friends Pedro, Chico and Jo‹o, this time went to Porto to spend a vacation. Of course, they took Faial and Caracol with them. On the train they were very lucky, because they met Rita and her dog Boxie. Rita had a huge group of cousins and friends with whom she used to organize lots of programs. Together they ended up living an exciting adventure. It all started with the discovery of a tunnel. Where would it go? Would it be dangerous to exploit it? Would it really be under the Douro, as the legends claimed?.