Controversial Catholic group Opus Dei has complained to the BBC about what it says is a "defamatory" portrayal in primetime drama Waking The Dead.
Sue Johnston stars as forensic psychologist Grace in the show
Two episodes of the crime series, shown last weekend, featured devotees of the religious organisation embroiled in a gruesome double murder.
Opus Dei said the BBC broke religious guidelines by showing its members as "murderers, thieves and adulterers".
The BBC said it had not yet received an official complaint.
Opus Dei was formed in 1928 in Madrid by the priest Josemaria Escriva de Balaguer. Its name means "the work of God".
It encourages members to see religion as something that should direct every minute of their lives, rather than being a matter of just turning up for Mass and confession.
But it has aroused controversy in the past, with critics calling it secretive and ultra-conservative, claims which its members deny.
Dan Brown's Da Vinci Code novel famously painted the organisation as a power-hungry movement bent on covering up the truth about Christ's bloodline.
Opus Dei claim it was this portrayal of their organisation that was the inspiration for Waking The Dead.
"The three characters portrayed as members are self-serving hypocrites whose main reason for belonging to Opus Dei is depicted as being their wealth," it said.
Opus Dei founder Josemaria Escriva de Balaguer has been canonised
"This portrayal is lifted from the Da Vinci Code, a book and film which claimed - against all evidence - to be based on fact."
The group says the BBC has broken its own editorial guidelines on religion, which state: "We will ensure the religious views and beliefs of an individual, a religion or religious denomination are not misrepresented".
A BBC spokeswoman said the complaint would be dealt with using the "usual procedure" once it had arrived.
"We cannot comment on something we have not yet received," she added.
Sunday's episode of Waking The Dead, entitled The Fall, was seen by 7.2m people.