Off the southwest side of the peristyle was a cult room. This was believed to have been located in the service quarter. The room had a rectangular plan and was open on two sides due to low walls on the north and south sides of the room. In the centre originally stood a square masonry altar, with a rectangular niche in the centre of the south wall, sitting 1.25m above the floor. The niche was adorned with a marble aedicula façade which consisted of plain rectangular slabs/pilasters on either side supporting a pediment above and a projecting base at the bottom. Within the niche was a low step against the back wall, and a circular depression (presumably for offerings) was present in front. On the pediment was painted an owl, with the Lares painted on either side of the niche, holding rhyta and situlae, and standing between two trees. Above was a garland with taeniae, with birds present above the Lares. Further paintings were present on the eastern wall, containing the famous panel of Bacchus as a bunch of grapes standing beside Mt Vesuvius, He held his thyrsus and poured wine from a kantharos onto the panther at his side. A vineyard/grape vines can be seen growing on the left side of the mountain. On the other side of the mountain was a bird in flight. Above was another bird perched on a garland of green leaves and red flowers with taeniae. In the lower level of the painting was a single brown and yellow serpent moving towards a cylindrical altar painted in imitation marble. The serpent was among green plants. A painted dado of imitation marble ran around the room. Today the panel from the eastern wall can be found in the Naples museum. The remaining decoration of the shrine is not well preserved today.