"ALIENS HAVE LANDED" (Book 5)

Lucy, eleven-year-old Robbie's sister, is about to celebrate he 15th birthday, Single minded, as she usually appears, she wants a big party. Dad has already said 'NO' to hiring the local church hall, but agreed to using the house on the conditions of limiting the number of invited guests and, worse, stipulated that Robbie is allowed to attend and invite a guest.
From the start of the party day, in spite of the two appearing to co-operate, there are a few trifling problems.
As party time looms, Mum and Dad, along with Auntie Sheila and Uncle Roger have barricaded themselves upstairs in the front bedroom with phone communication to Robbie.