Russell T Davies (Queer as Folk) has penned It's A Sin, a brand new five-part drama series about the 1980s AIDS epidemic, featuring a cast of newcomers led by actor and pop singer Olly Alexander.
The series follows three young gay men and flatmates who all move to London filled with hope and ambition, while inadvertently "walking straight into a plague that most of the world ignores".
The series has already proved a hit among viewers and critics alike, having begun on Friday 22nd January on Channel 4, and the whole series made available to stream as a box-set on All4 (US viewers will have to wait until February).
In addition to the central characters and residents of 'The Pink Palace' flat share, the series stars the likes of Keeley Hawes, Stephen Fry, and Neil Patrick Harris.
Read on for everything you need to know about the cast and characters of It's A Sin.
Olly Alexander plays Ritchie Tozer
Who is Ritchie Tozer? Hailing from the Isle of Wight, Richie is a young gay man who moves to London to start his law degree in It's A Sin episode one. He's fun, frivolous, and initially inexperienced. Back home his parents are conservative with a small 'c', and he still hasn't come out to them.
Where have I seen Olly Alexander before? He's best known as the lead singer and frontman of band Years & Years (coincidentally, Russell T Davies' BBC One drama had the same name). Alexander has also acted in the likes of Bright Star and Funny Bunny.
Omari Douglas plays Roscoe Babatunde
Who is Roscoe Babatunde? An 18-year-old whose Nigerian family effectively disown him when he comes out (which he does in spectacular style), Roscoe is bitchy and brave, and intends to become fabulously wealthy in later life.
Where have I seen Omari Douglas before? This is Omari Douglas's first major on-screen role.
Callum Scott Howells plays Colin Morris-Jones
Who is Colin Morris-Jones? Nicknamed "Gladys Pugh" (the Welsh actress known for Hi-de-Hi!), Colin is a sweet-tempered young man from Wales, and he moves to London with the hopes of becoming a Savile Row tailor. It's here that he meets his mentor Henry, who helps him come to terms with his own sexual orientation.
Colin's storyline was partly informed by real-life events (you can find out more about the It's A Sin true story here).
Where have I seen Callum Scott Howells before? This is the newcomer's first major on-screen role.
Lydia West plays Jill Baxter
Who is Jill Baxter? Based on an "inspiring" real-life person, Jill is a kind, funny drama student who meets both Ritchie and Ash at university in London, becoming best friends with the former. She also helps convince Ritchie that he might be better suited to a drama course.
Where have I seen Lydia West before? West is known for her roles in Dracula (as Lucy) and BBC One's Years and Years.
Nathaniel Curtis plays Ash Mukherjee
Who is Ash Mukherjee? A dreamboat, introspective drama student whom Ritchie immediately falls for when he spots him rehearsing with Jill.
Where have I seen Nathaniel Curtis before? The newcomer makes his on-screen debut in It's A Sin.
Keeley Hawes plays Valerie
Who is Valerie? Ritchie's frumpy mother who lives on the Isle of Wight, and who initially seems downtrodden by her occasionally aggressive husband, Clive.
Where have I seen Keeley Hawes before? The actress is known for the likes of Line of Duty, Bodyguard, Ashes to Ashes, The Durrells, Summer of Rockets, Year of the Rabbit, and the recent true crime drama Honour.
Shaun Dooley plays Clive
Who is Clive? Ritchie's brusque father, who is oblivious to his son's sexual orientation.
Where have I seen Shaun Dooley before? He's known for The Woman in Black, The Awakening, Official Secrets, Eden Lake, The Witcher, and the BBC period drama Gentleman Jack.
Neil Patrick Harris plays Henry Coltrane
Who is Henry Coltrane? A well-spoken British tailor who lives with his gay partner - a living arrangement that's an open secret down his street.
Where have I seen Neil Patrick Harris before? He's best known for playing Barney in the long-running comedy sitcom How I Met Your Mother. He's also starred in the likes of Gone Girl, Glee, A Series of Unfortunate Events (the TV version), and American Horror Story.
Stephen Fry plays MP Arthur Garrison
Who is Arthur Garrison? A politician desperate to impress Margaret Thatcher - and keep his personal life well-hidden. He appears in It's A Sin episode three.
Where have I seen Stephen Fry before? The actor, comedian, and TV presenter is known for the likes of QI (which he formerly hosted), Gosford Park, Wilde, V for Vendetta, Sex Education, Jeeves and Wooster, and Blackadder Goes Forth.
Tracey Ann Oberman plays Carol Carter
Who is Carol Carter? Acting agent Carol first appears in episode one, in which she interviews Ritchie.
Where have I seen Tracey Ann Oberman before? The actress is known for starring in EastEnders, Filth, Doctor Who, After Life, Friday Night Dinner, and Grantchester (as Sister Grace).
Ruth Sheen plays Sandra
Who is Sandra? The hospital visitor and mother who confronts Keeley Hawes' character, Valerie, in It's A Sin episode five.
Where have I seen Ruth Sheen before? She starred in Unforgotten, and has previously appeared in Brassic, Moving On, Another Year, Vera Drake, and Run Fatboy Run.
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Andria Doherty plays Eileen Morris-Jones
Who is Eileen Morris-Jones? Colin's devoted mother ("Mammy") from Wales. Colin has not yet come out to her at the start of the series.
Where have I seen Adria Doherty before? She's previously appeared in Doctors and the series Gwaith/Cartref.
It's A Sin airs on Channel 4 on Fridays at 9pm, with all episodes now available on All 4. Looking for something else to watch? Check out our TV Guide.