When Mel skips school to visit her mother's grave (she won't explain why at first) her teacher Mr Coleman decides it's time to pay a home a visit. Meanwhile, Brian has developed an allergy that causes him to sneeze and morph uncontrollably. Mel starts training Sophie to behave like a 'real' mother, while Lucy attempts to diagnose Brian's allergy. Unfortunately, during his visit Mr Coleman sees Brian sprout a new nose and ears, and resolves to return with their social worker. Josh is determined to hold a party to improve his social standing – could this somehow save the whole family from being taken back into care? Will the world find out Brian and Sophie are aliens?

Mel arrives home late and expects to be grounded by Brian and Sophie but isn't. She keeps trying to get into trouble until she comes home with a walkman she says she stole. Josh tries to get a date with Tanya Thomas (Zoe Thorne), so he enlists Brian's help. Brian morphs into Josh and asks out Tanya's friend, Denise, who fancies him. When the two girls meet each other on the day of the date, they both start hating Josh.

Mel finds out that the children have or had an aunt and uncle in Canada who look suspiciously like Brian and (the original) Sophie. They confront Brian and Sophie, who admit that, seven years ago, they met Josh, Mel and Lucy's aunt and uncle at the children's home – and then, after the aunt and uncle realized that they were aliens, the aunt and uncle were kidnapped and kept in suspended animation in the attic for seven years. The children insist that they let them free. Meanwhile, Wendy discovers Brian and Sophie are aliens, and she tells Pete and Frankie too, so Brian wipes their memories. Everyone realizes that it is time to move on. Josh, Mel, Lucy, Harry and CJ all move to Canada with the real Brian and Sophie Johnson, and the aliens appear to go back home to Valux; however, Brian presses the big red button that caused the pair to crash-land on Earth in the first place setting the stage for series 8. They land by the sea and then head for the foster home.

Harry does her best to stop Brian and Sophie inviting Trent's parents to tea. Harry learns a "shocking" secret about Trent, Sophie gets into growing vegetables and Brian gets into football.

Lucy discovers she and her best friend are 'geeks' after they are the only two girls in the class not to be invited to a party. Mel gives Lucy a makeover, but this threatens to alienate her from Wendy, with whom she has been studying caterpillars. Sophie is struck down with a case of the flu, but enjoys her freedom from housework and responsibility and hides her recovery. Lucy decides friendship is more important than being 'cool', and she and Wendy discover that their caterpillars "were really butterflies all along."

When Lucy wants Brian's help with her magic act, his ambitions go far beyond being her assistant. Mel runs in the school's sponsored FunRun with Andy the freak in a pantomime horse costume.

Brian decides that he and everyone else should become a proper family so Brian enters a quiz night, however Lucy doesn't want to join so she goes to join Wendy's team and ends up playing against her family who will win and what will happen?

Mel goes to school in trousers, as she feels the school rule that girls must wear skirts is sexist, whilst Lucy is looking after the school hamster which Josh promptly loses by trying to make some money with it.

When Lucy calls Brian and Sophie "Mum and Dad", Mel gets angry and shows Lucy and Josh a box of things she kept to remind her of their real parents. However, a lipstick is missing from the box. Lucy realizes that it was she who had taken it and swapped it, so she must ask Josh for help. Meanwhile, after a string of Fs, Josh must resit his exams or be put back a year. To pay him back for helping with the lipstick, Lucy helps him revise, and discovers that he may be dyslexic.

Josh and Brian vie to see which of them can tell the scariest Hallowe'en story, but Sophie can't understand why it's fun to be frightened.

Harry gets angry with Sophie for not providing for her properly, even though she is doing the best she can. The example of this is Cold Scrambled eggs. This gives Sophie the idea of opening a hotel, so that she can at least get paid for running around after people. Guests start to arrive at the house, and Brian causes chaos by messing with the central heating.

Mel asks Scott Taylor to the school Christmas disco, causing Trent to get jealous. Lucy is cast as Mary in the Nativity play, a part Wendy wants. Josh fills Brian and Sophie in about Christmas. Lucy gives Wendy the part of Mary in the play, but Wendy becomes extremely demanding. Mel gets cold feet and won't go to the disco, so Brian morphs into her and goes in her place. Mel finds out and rushes to the disco, only to find Brian-Mel kissing Scott, right in front of a heart-broken Trent! Mel attempts to repair the damage caused by Brian, only to find out some things about herself. The school Nativity play becomes a strain on Lucy and Wendy's friendship. Josh has nightmares and is visited by ghosts in a plotline similar to that of Dickens A Christmas Carol.

"Great Versace's ghost!" Brian cries as he takes the role of fashion designer and forces the children to wear his fruity clothes and curtains. Meanwhile, Sophie collaborates with Josh in yet another fraudulent scheme, this time a pet selling scam involving a pot bellied pig, and a lot of icecream...

Sophie learns about gossip and thinks that Mrs. Hardman and Mr Whiteside have fallen in love with each other. Brian finds a human toe in his can of cola and finds out the drink was faulty and complains before he tests CJ’s eyes and discovers that he too is ‘faulty’. Josh competes in a snail race against Poppy, and the winner gets £5. Josh is convinced he'll win but when his snail is about to win Mrs Hardman comes in and Josh accidentally sits on his snail (Lenny) killing it.

Harry signs up for a boxing tournament after Trent says girls shouldn't compete in the sport, but her confidence takes a knock when she sees her opponent. Brian is bullied by a little schoolboy and Sophie dresses up as a hamburger.

Mel asks Scott Taylor to the school Christmas disco, causing Trent to get jealous. Lucy is cast as Mary in the Nativity play, a part Wendy wants. Josh fills Brian and Sophie in about Christmas. Lucy gives Wendy the part of Mary in the play, but Wendy becomes extremely demanding. Mel gets cold feet and won't go to the disco, so Brian morphs into her and goes in her place. Mel finds out and rushes to the disco, only to find Brian-Mel kissing Scott, right in front of a heart-broken Trent! Mel attempts to repair the damage caused by Brian, only to find out some things about herself. The school Nativity play becomes a strain on Lucy and Wendy's friendship. Josh has nightmares and is visited by ghosts in a plotline similar to that of Dickens A Christmas Carol.

On Halloween, Josh has a plan to run a tour of the school, with Frankie and Pete helping to spook the students. Mel wants a Halloween party but is so scared that no one will turn up that she advertises the event as Trent's party. However, no-one wants to come a party held by Trent either and the two of them turn out to be the only ones there. During this episode there is one of the many obviously romantic moment between Mel and Trent when they almost kiss in Mel and Lucy's bedroom.

Sophie decides to accompany Lucy to advanced mathematics classes after school, but it soon becomes clear that Sophie has fallen in love with Mr. Whiteside, the teacher. Brian feels that he is losing Sophie (and her ability to cook disgusting meals which deeply satisfy Brian) to Mr. Whiteside, so he sneaks into school and kidnaps Mr. Whiteside, and then morphs into Mr. Whiteside himself, to try to pretend to Sophie that Mr. Whiteside is "evil". Unfortunately his plan is ruined when Sophie invites Brian and Mr. Whiteside to have a meal together with her.

Josh introduces Brian to a weekend of slobbing and Mel teaches Brian about manners. Josh bets with Mel that he can turn Brian into a gentleman and he does it, but Brian turns into an old grump. Also he invites Trent (whom Brian calls 'Trentington') round for dinner with disastrous results. So now, they've got to make Brian back to normal.

Lucy finds an injured dog, which she names Dennis, and starts nursing it back to health. Mel disapproves, warning Brian that Lucy will be upset when it dies. Meanwhile, Josh spends the money he raised for a charity event on a football ticket, and starts to earn the money back by putting up 'dog found' posters for Mel. When Lucy finds out, she pays him even more to bring them all back again, by which time Mel has warmed to Dennis and agrees to keep him. However, Josh returns with a 'Have you seen Woolly?' poster and Lucy and Mel realize that Dennis, a.k.a. Woolly, needs to go home to the people who are missing him.

When Lucy wins tickets to see Blink 182 in a competition, Josh is desperate to take them off her hands – after all, he's a huge fan of the band, and Lucy's such a geek she's never even heard of Blink 182. Lucy agrees to give the tickets to Josh, but on one condition: Josh has to perform a truly unselfish deed in order to qualify for the tickets. Of course it's a terrible struggle for the scam-meister, but Josh learns a whole lot about himself in the process. Elsewhere Mel is upset (though refuses to show it) when Trent appears to be going on a date with another girl. The confusion is resolved later in the episode when it turns out that Kelly is Trent's cousin, not his date and he and Mel become friends again.

Josh injures himself during sports, so Brian attempts to fix him with a home-made machine. However, the machine instead makes Josh a chess champion and a maths prodigy by mistake, making Lucy feel threatened as she is outplayed in chess.

Josh wants to have a wild party for his class (including resident tough-guy, Big Verne) so he tries to make the rest of the family go on a holiday. Mel is aggravated by her family's constant need for attention when all she wants some privacy to write a song to enter into a competition with Trent.

Lucy and Wendy are on the verge of falling out, as Wendy is upset that Lucy never invites her to her house. They arrange a sleepover, and Sophie and Brian must act as normal as possible. Meanwhile, Josh is charging Sophie for doing chores around the house so that he can later buy a snooker table.

Lucy is selected to represent the school in a Science Tournament where she has to build a rocket with maximum propulsion – which proves to be too difficult a task for her, so Sophie offers to help. Brian enters one of Mel's photograph's in an art contest. Josh tries to bribe Scott Taylor into letting him join the football team and get to go to Holland and almost loses Frankie and Pete as friends.