Question: How many people were murdered by the serial killer featured in the drama series In Plain Sight?

Context paragraphs:
Peter Manuel: Peter Thomas Anthony Manuel (13 March 1927 – 11 July 1958) was an American-Scottish serial killer who was convicted of murdering a total of seven people across Lanarkshire and southern Scotland between 1956 and his arrest in January 1958, and is believed to have murdered two more, nine in all.  Prior to his arrest, the media nicknamed the unidentified killer "the Beast of Birkenshaw".  Manuel was hanged at Glasgow's Barlinnie Prison; he was one of the last prisoners to die on the Barlinnie gallows.

In Plain Sight (UK TV series): In Plain Sight is a Scottish television drama series covering the crimes committed by serial killer Peter Manuel in Lanarkshire, Scotland in the 1950s.  The three-part series was first broadcast on ITV on 7 December 2016.

Evan Frankfort: Evan Frankfort (born December 13, 1970) is an American teleivison/film composer, sound designer, engineer, and music producer.  He has composed music for several shows and films including "Rules of Engagement", "Swingtown", "In Plain Sight", and "90210".  He has also contributed to over 100 records, working with artists including Plain White T's, Liz Phair, Rancid, Flock of Seagulls, The Dollyrots, and many more.

Dexter (episode): "Dexter", or "Pilot", is the pilot episode of the first season television drama series "Dexter", which premiered on October 1, 2006 on Showtime in the United States.  The episode was written by developer James Manos, Jr. and directed by Michael Cuesta.  It was based on the opening of the novel "Darkly Dreaming Dexter" by Jeff Lindsay.  The pilot introduces the series' protagonist, Dexter Morgan (Michael C. Hall), a Miami Metro Police Department blood spatter analyst with a double life as a serial killer.  While solving murders in the Homicide division, Dexter also spends his time hunting and killing murderers and criminals who have escaped the justice system.  The pilot introduces the "Ice Truck Killer", a serial killer who targets prostitutes and leaves their bodies dismembered and bloodless, and the rivalry that develops between the killer and Dexter.

Holly Maples: Holly Maples (DOB unknown) is an American actress.  She is probably best known for playing secretary Eleanor Prince on the USA Network drama series "In Plain Sight" and is the wife of the series' creator David Maples.

Cold Fish: Cold Fish (冷たい熱帯魚 , Tsumetai Nettaigyo ) is a 2010 Japanese horror-drama serial killer film directed by Sion Sono.  The film is about a quiet and unambitious owner of a tropical fish shop whose life and family are taken over by a fellow fish entrepreneur who happens to be a serial killer.  The film is loosely based on the exploits of two Tokyo serial killers, Sekine Gen and Hiroko Kazama, a husband and wife duo who owned a pet shop and murdered at least four people.

Jill Eikenberry: Jill Susan Eikenberry (born January 21, 1947) is an American film, stage, and television actress.  She is known for her role as lawyer Ann Kelsey on the NBC drama "L.A. Law" (1986–94), for which she is a five-time Emmy Award and four-time Golden Globe Award nominee, winning the Golden Globe for Best Actress in a Drama Series in 1989.  She received an Obie Award in 1986 for the Off-Broadway plays "Lemon Sky" and "Life Under Water", and was nominated for a 2011 Drama Desk Award for the Off-Broadway musical "The Kid".  Her film appearances include "Hide in Plain Sight" (1980), "Arthur" (1981) and "The Manhattan Project" (1986).

Rachel Boston: Rachel Elizabeth Boston (born May 9, 1982) is an American actress and producer.  Boston had leading roles in a number of independent films, and was a regular cast member in several television series.  She starred in the NBC drama series, "American Dreams" as Beth Mason from 2002 to 2005, and later co-starred in the short-lived CBS sitcom "The Ex List" and on the USA Network series "In Plain Sight".  From 2013 to 2014, Boston starred as Ingrid Beauchamp in the Lifetime fantasy-drama series, "Witches of East End".

Long Island serial killer: Long Island serial killer (also referred to by media sources as the Gilgo Beach Killer or the Craigslist Ripper) is an unidentified suspected serial killer who is believed to have murdered 10 to 16 people associated with prostitution, over a period of nearly 20 years, and dumped their bodies along the Ocean Parkway, near the remote Long Island, New York beach towns of Gilgo Beach and Oak Beach in Suffolk County, and the area of Jones Beach State Park in Nassau County.

Greenskeepers: Greenskeepers are an indie rock/new wave band from Chicago.  Their song "Lotion" is a tribute to the character Buffalo Bill, the fictional serial killer featured in the 1991 film, "The Silence of the Lambs".  "Lotion" also came in at #90 in the 2004 Triple J Hottest 100.

Supporting paragraphs: In Plain Sight (UK TV series) Peter Manuel
Answer: seven