Another actress has joined the ever growing cast of FX's American Horror Story: Hotel.

'Hot Pursuit' Actor Joins 'American Horror Story: Hotel' As Homicide Detective

Helen Mattsson, who has guest starred on such shows as ABC's Mistresses, FX's Fargo and The CW's Nikita, will star in American Horror Story: Hotel. The actress revealed the news herself on her Instagram page.

"Another day at work. Getting ready to film some scary stuff #thatsallicansay #americanhorrorstory", she wrote, alongside a photo outside of a studio lot.

Evan Peters Wants To 'Bro It Up' With Male Co-Stars In 'American Horror Story: Hotel'

 Another day at work. Getting ready to film some scary stuff.. #thatsallicansay #americanhorrorstory

A photo posted by Helena Mattsson (@helena_mattsson) on Jul 15, 2015 at 7:33pm PDT

It is unknown how significant Mattsson's role will be on the show.

Mattsson joins previously announced stars Lady Gaga, Sarah Paulson, Kathy Bates, Angela Bassett, Evan Peters, Denis O'Hare, Finn Wittrock, Matt Bomer, Wes Bentley, Cheyenne Jackson, Chloë Sevigny, Max Greenfield, Emma Roberts and Richard T. Jones, all of whom are checking into Hotel.

Filming was scheduled to begin this month.

Very little has been revealed about Hotel, other than some character names and few relationships between the characters. Announced character names are as follows:

Paulson - Hypodermic Sally

Bates - Iris

Bassett - Ramona

Peters - Mr. March

Bomer - Donovan

American Horror Story boss Ryan Murphy said that all of these characters will be villains in their own ways.

He also revealed on Twitter that Gaga, Bomer and Wittrock's characters will be involved in a love triangle of sorts. Additionally, Bassett's Ramona will spend time with Gaga's character in the ballroom of the hotel.

Murphy also said that Peters' Mr. March will have something to do with "Room 64," which cannot be good.

American Horror Story: Hotel premieres in October on FX, though the network has not yet announced a specific premiere date.