The secret files called the Zacharis Dossier may cause a war between the East and the West. In order to obtain a painting that is supposed to be the hiding spot for these files, Loid and Fiona enter an underground tennis tournament run by the owner of the painting, Campbell. If they win, the art piece they're after will be presented. Loid and Fiona enter as a married couple and play various skilled players including pro players!
It's located in the basement of the Campbell 
mansion along with his other art pieces.
.إنّها في قبو في قصر كامبل مع بقيّة تحفه الفنّيّة
Bei den anderen Kunstgegenständen
im Anwesen Campbells.
En el sótano de la mansión de Campbell,
junto a otras piezas de arte.
En el sótano de la mansión de Campbell,
junto a otras piezas de arte.
Campbell l’a mise avec sa collection,
au sous-sol de sa résidence.
Nel caveau della villa di Campbell,
insieme ad altre opere d'arte.
No porão da mansão Campbell,
assim como outras obras de arte.
В подвале особняка Кэмпбеллов
вместе с другими произведениями искусства.