Girls Nite Out (also known as The Scaremaker) is a 1982 American slasher film written and produced by Anthony N. Gurvis, directed by Robert Deubel, and stars Julia Montgomery, Suzanne Barnes, Rutanya Alda, and Hal Holbrook.
 The film focuses on a group of college girls who are targeted by a killer in a bear mascot costume during an all-night scavenger hunt on their campus.
Savage Weekend is a 1979 American slasher film directed by David Paulsen and starring Christopher Allport, David Gale, William Sanderson, and Caitlin O'Heaney.
 The film follows a woman who retreats to upstate New York with her wealthy boyfriend, her sister, and friend, only to be stalked by a killer in a disfigured mask.
 Filmed in 1976 as "The Killer Behind the Mask", the film was also titled "The Upstate Murders" before being released in 1979 by Cannon Films.
 It has been cited as an early prototype for the slasher film, predating "Halloween" and "Friday the 13th".
Fatal Games (originally known as The Killing Touch and also released as Olympic Nightmare) is a 1984 American slasher film written and directed by Michael Elliott and starring Sally Kirkland, Lynn Banashek, Sean Masterson, Michael O'Leary, Teal Roberts, and Spice Williams-Crosby.
 The plot consists of a mad slasher wielding a javelin killing off various members of a high school gymnastics team.
 The film shares many of its plot points with an earlier slasher film, "Graduation Day".
Home Sweet Home (also known as Slasher in the House) is a 1981 American slasher film directed by Nettie Peña, and written by Thomas Bush.
 It stars Jake Steinfeld, Peter De Paula, and Vinessa Shaw in her film debut, and the plot focuses on a PCP-addicted killer who terrorizes a family in their remote home on Thanksgiving.
 Along with "Blood Rage" and the faux "Thanksgiving" trailer from "Grindhouse"), it is one of the few slasher films centered on the Thanksgiving holiday, and one of the few to be directed by a woman.
Michael Myers is a fictional character from the "Halloween" series of slasher films.
 He first appears in John Carpenter's "Halloween" (1978) as a young boy who murders his older sister, then fifteen years later returns home to murder more teenagers.
 In the original "Halloween", the adult Michael Myers, referred to as The Shape in the closing credits, was portrayed by Nick Castle for most of the film, with Tony Moran and Tommy Lee Wallace substituting in during the final scenes.
 The character was created by Debra Hill and John Carpenter and has appeared in nine films, as well as novels, multiple video games, and several comic books.
Halloween 4: The Return of Michael Myers is a 1988 American slasher film and the fourth installment in the "Halloween" film series.
 Directed by Dwight H. Little and written by Alan B. McElroy, it focuses on Michael Myers returning home to kill his niece Jamie Lloyd (Danielle Harris), the daughter of Laurie Strode, with Dr. Sam Loomis (Donald Pleasence) once more pursuing him.
Halloween is a 1978 American slasher film directed and scored by John Carpenter, co-written with producer Debra Hill, and starring Donald Pleasence and Jamie Lee Curtis in her film debut.
 The film is the first installment of the "Halloween" franchise.
 In the film, on Halloween night in 1963, Michael Myers murders his sister in the fictional Midwestern town of Haddonfield, Illinois.
 He escapes on October 30, 1978 from Smith's Grove Sanitarium, and returns home to kill again.
 Michael's psychiatrist, Dr. Sam Loomis, knowing Michael's intentions, gives chase.
 The next day, Halloween, Michael stalks teenager Laurie Strode.
Jonny Briggs is a Children's BBC kitchen sink realism television programme first broadcast in 1985.
 It revolves around the exploits of a young boy, the eponymous hero (played by Richard Holian), his pet dog, Razzle, and his eccentric family members: Mam (Jane Lowe) and Dad (Leslie Schofield), older sister Rita (Sue Devaney) and older brothers Albert (Tommy Robinson) and Humph (Humphrey) (Jeremy Austin).
 Another older sister, Marilyn, is mentioned but never seen.
 The stories often centre on Jonny's school life, where he and his best friend Pam are constantly in battle with the dreadful twins Ginny and Josie.
Cheerleader Camp (originally titled Bloody Pom Poms) is a 1988 American slasher film directed by John Quinn, and starring Betsy Russell, Leif Garrett, Lucinda Dickey, George "Buck" Flower, Teri Weigel, and Rebecca Ferratti.
 The plot follows a series of murders that occur over a weekend at a cheerleader camp during a competition.
A piano virtuoso has a child out of wedlock to her fiance, who is killed trying to save her life.
 Their son is brought up by foster parents and becomes a musician.
"In 1917, Carlo Salvini (George F. Houston), an opera singer and captain in the Italian army, returns home to participate in a performance of "Carmen" for a Red Cross benefit.
 Afterward, Carlo meets Franceska Manzoni (Helen Westley) and her niece, pianist Ann Prescott (Josephine Hutchinson).
 When German troops move closer to the village, Carlo and his fellow soldiers help Franceska, Ann and the other villagers evacuate.
 Before Carlo can get away, however, the German troops invade and Ann hides him in the attic.
 During the ensuing months, Ann and Carlo fall in love and marry.
 Carlo returns to the front line, and later Ann gives birth to their son, whom she names Carlo.
 Then, Franceska, who was her piano instructor too, dies, and her final wish is for Ann to dedicate young Carlo's life to music.
 In order to save her baby from the enemy concentration camp, Ann turns him over to the custody of a Dominican convent.
 After Ann learns that Carlo has died, she returns to the convent, but the Mother Superior (Laura Hope Crews) informs her she cannot have custody of Carlo without a husband.
 Desperate, Ann decides to enter the convent as a nun, and is able to ascertain which child is her own.
 Ann is forced to leave the order, however, when she is caught trying to leave with the baby.
 Ann returns to her family villa, immerses herself in the piano, and becomes an acclaimed concert pianist.
 Years later, after hiring an agency to track her son, Ann learns that Carlo was adopted by diplomat Marco Turina (John Halliday) and his wife Sylvia (Mona Barrie).
 A friend, Groce (Walter Kingsford), helps Ann get invited to a party at the Turina home, and there Ann sees Carlo, who is now called Guido Turina (David Scott) and is a young college student.
 A bond between Guido and Ann develops, and he confides to her that he feels a strange calling to become a musician, although his father plans for him to follow the long line of Turina men and become a diplomat.
 In order for Ann to continue to see Guido and coerce Marco to allow the boy to sing, she develops a friendship with Marco, but Sylvia misconstrues the relationship, and a desperate Ann is forced to confront her.
 Ann reveals Guido's parentage to Sylvia so that Sylvia will help the young man fulfill his true destiny.
 Ann agrees to leave, but receives her life's wish when Guido becomes an opera star."

Question: This 1988 American slasher film focuses on a fictional character who as a young boy who murders his older sister then returns home how many years later?
Answer: fifteen