Seren and Huw realise that they forgot Liam's birthday. But with Seren having a whole day of lectures ahead, can she trust Huw to organise a celebration without him turning it into a big party?
A Russian hacker locks the crew out of the house WiFi. Huw decides they need to get to know each other better and organises a board games night. As the game's progress, Huw introduces something a little different to the proceedings.
During international rugby weekend, Huw's cousin, Hywel comes to stay. But as the weekend proceeds, something about Hywel's behavior doesn't sit right with Seren and Liam.
Seren has decided that she wants to be a dominatrix and finds a teacher who is ready to immerse her in the field, much to Huw's dismay. But when the sound of rats begins to fill the house at midnight, Huw has other things to think about.
When Huw's parents arrive unannounced, the crew know something big is afoot. But as Huw disappears on an important task, Seren and Liam have to work together to make sure they have a future in the house.