Halloween gets a suitably spooky thriller tonight as Joanne Froggatt returns to period drama - this time as a Victorian poisoner.
The actress, who played ladies' maid Anna Bates in ITV's hit series Downton Abbey, is back with the channel again, starring in a sinister role for two-part drama Dark Angel, which is based on historical events.
Froggatt, 36, plays Mary Ann Cotton, a poverty-stricken woman living in north-east England in 1857 who committed a series of grisly murders to bolster her finances and boost her social standing.
Cotton's victims included her husbands and even her own children as she fought to make a more comfortable life for herself by claiming life insurance policies, using tea laced with arsenic as her method of choice.
Also starring in the programme are Alun Armstrong, who plays Cotton's stepfather, and Jonas Armstrong as her lover Joe Nattrass.
Froggatt said: "Although Dark Angel is a period drama, Mary Ann could not be more different from Anna Bates.
"This is totally different to Downton."
The two-parter was inspired by David Wilson's book Mary Ann Cotton: Britain's First Female Serial Killer, and was filmed in County Durham and North Yorkshire.
It was directed by Downton Abbey's Emmy and BAFTA award-winner Brian Percival.
Dark Angel airs on ITV at 9pm and concludes on November 7.