Cilla and Tina are identical twins. They are fourteen years old and have typical teenage problems. Cilla is down to earth, slightly tomboyish and an outcast in their class. Tina is popular, boy-crazy and somewhat shallow. One morning when they are late for the bus to school and race across the street to catch it Cilla is hit by a car and dies. The remainder of the story follows Tina in the first year after her sister's death as she struggles to live her life without her twin, deals with her sorrow and attempts to live a normal teenage life.
The book is co-written by Peter Pohl and Kinna Gieth. Pohl is a popular Swedish writer of youth fiction and his book "''Alltid den där Anette''" deals with the topic of a character losing their twin. Kinna Gieth and her identical twin sister Jenny read the book together and talked about how they wouldn't be able to go on if the other died. Two weeks later Jenny was killed in a car accident. Gieth contacted Pohl and asked him to help her tell her story and the resulting book is a mixture of fact and fiction, based on the diaries of the Gieth twins, interviews with Kinna and her family and correspondance between Gieth and Pohl.
Nineteen years after the book was published a movie was released, the title shortened to "''I Miss You''". Noteable changes in the movie include leaving out the twins' stepbrother Jonny, changing the name of a character from Bahir to Ailu and making the twins' father Italian rather than French.
!!The book and film provide examples of:
* AdultFear: Your child being run over and killed on the way to school.
* AgeAppropriateAngst: Most of what the twins angst over prior to Cilla's death.
* AlphaBitch: Anna-Karin and Maja.
* AmateurCast: None of the actors playing teenagers in the movie had acted professionally before.
* BadDreams: Tina suffers from nightmares about Cilla. So do the twins' parents.
* BasedOnATrueStory: Only Pohl and Gieth know which parts are fact and which parts are fiction.
* CatapultNightmare: Tina in the movie.
* CompositeCharacter: In the movie Jonny's friend Martin and Bahir's musical partner Ola are combined into one and it works surprisingly well.
* DemotedToExtra: Cilla's best friend Sandra and Tina's best friend Lotta, who play a much larger and more significant role in the book than in the movie. Poor Lotta never even gets named in the film. Still they are more lucky than the twins' stepbrother Jonny who isn't in the movie at all.
* DoggedNiceGuy: Poor Fredde.
* TheDulcineaEffect: Arguably Bahir/Ailu. He meets Cilla when she asks him to write music for her play, instead he writes a song for her ("''Cilla Suite''" in the book, "''Cilla Turns''" in the film) despite not knowing her and being at least a couple of years her senior. After her death he writes her another song ("''Memorial Cilla''" in the book, "''Jag Saknar Dig''" in the film) which he performs at the funeral. After the first song becomes a hit he is obsessed with perfecting it and asks Tina to help him out by playing the violin on the track. The way his musical partner Ola comments on it in the book it seems like he's working on the song as part of his grief process. All this for a girl he barely knew.
* EmbarrassingFirstName: Not embarassing per se but the twins were born in France and given French names. After the move to Sweden their new stepbrother decides you can't go around normal people with names like Martinelle and Cilibelle and nicknames them Tina and Cilla.
* FaceOfTheBand: In the film Ailu is this for his band.
* FirstLove: Cilla thinks Tina needs to experience this. She does eventually but he turns out to be less of a Prince Charming than she thought.
* ForeignLanguageTirade: Albert on occasion.
* GoryDiscretionShot: We don't get to see much of Cilla's body after the accident.
* InLoveWithLove: Tina while her sister is still alive.
* LookBothWays: Tina and Cilla run across the street without looking either way and Cilla gets hit. Tina later tells Martin, who was driving the car, that the accident was hers and Cilla's fault for not looking both ways before crossing the street.
* LoserGetsTheGirl: The ending implies that Tina starts a relationship with Fredde.
* MaybeEverAfter: Tina and Fredde.
* MirrorMonologue: Tina frequently carries out conversations with her mirror image, imagining that she's really talking to Cilla.
* OhAndXDies: Both the book and the movie open with Tina revealing that Cilla is going to die.
* PolarOppositeTwins: Tina and Cilla to some degree.
* RageAgainstTheReflection: Tina, taking her anguish over Cilla's death and her unresolved issues with her twin out on her mirror image. Complete with kicking the mirror in the movie.
* ShoutOut: Several to "''Allrakäraste Syster''" ("''Most Beloved Sister''"), a story by Creator/AstridLindgren about a girl who feels unloved by her family and imagines having an identical twin sister who loves her the most. Tina and Cilla refer to each other as "most beloved sister" and mention having loved the story growing up. The book opens with a passage from the story where the main character comes to terms with her twin not existing.
* SiblingSenioritySquabble: Tina is fifteen minutes older than Cilla.
* SurvivorGuilt: Tina was running just one step ahead of her sister when Cilla got hit.
* ThereAreNoTherapists: Semi-averted. Tina eventually agrees to see a counsellor.
* TheUnFavourite: Tina sometimes feels like her parents and brother prefer Cilla.
* WrongNameOutburst: People sometimes call Tina by her sister's name after the accident. Tina herself sometimes calls her friends Cilla.