repare to become obsessed with famous people backstabbing and betraying one another in a Scottish castle. Yes, autumn is upon us, meaning the return of last year's TV sensation, The Celebrity Traitors.

The inaugural VIP version of the BBC's reality gameshow proved a runaway hit and broke ratings records as Alan Carr chaotically schemed and sobbed his way to victory. The second series promises to be bigger, better and more murderous with extra episodes, shock twists and an even starrier lineup.

The cloaks are freshly laundered. Poisoned chalices have been polished. Claudia Winkleman has fluffed her pet owl's feathers. With less than a week to go, here's everything you need to know …

1. The famous faces

This year's contest has an expanded field of 21, up from 19, and has attracted what has been hailed as "one of the most high-profile casts ever assembled for a reality show". Filming took place from late May to early June in the now-familiar surroundings of Ardross Castle in the Scottish Highlands. The cast stayed 30 miles away at Inverness Airport's Courtyard by Marriott hotel.

The headline names – "Big Dogs", in Traitors parlance – are the actors Richard E Grant and Michael Sheen, the supermodel Jerry Hall and the comedian Miranda Hart, making a welcome TV comeback after years out of the spotlight due to chronic illness. They're joined by the singers James Blunt and Leigh-Anne Pinnock, formerly of girlband Little Mix, alongside soap royalty Ross Kemp (AKA EastEnders' Grant Mitchell) and Julie Hesmondhalgh (AKA Coronation Street's Hayley Cropper).

There are boffins in the mathematician Prof Hannah Fry and University Challenge quizmaster Amol Rajan, plus half a dozen relative youngsters: the actors Bella Ramsey, Myha'la, Sebastian Croft and Sharon Rooney, plus the Love Island presenter Maya Jama and the content creator King Kenny. The cast is rounded out by slightly too many comedians: Joanne McNally, Rob Beckett, Romesh Ranganathan, Joe Lycett and James Acaster.

2. The haute host

She might have bowed out of Strictly Come Dancing but fear not, Winkleman still presides over this contest, sporting her trademark fringe and talking-point wardrobe. "It goes a little Artful Dodger for this series," she admits. The presenter also confessed to corpsing regularly, adding: "Rob Beckett said something that made me hide in a bush until I composed myself."

3. The long-awaited airdate

Richard Osman caused a kerfuffle three weeks ago by letting slip the embargoed launch date. During a live edition of The Rest Is Entertainment podcast, he let slip that the series would start on 23 September. Cue sighs of relief at Traitors HQ because Osman was wrong.

The mind games actually begin on Thursday 1 October at 8pm on BBC One, kicking off with an extended 75-minute opener. There's also a one-off bonus show, Traitor or Faithful? Claudia Decides, exclusive to BBC iPlayer and revealing how La Winkle chooses her cloaked conspirators.

4. The series schedule

The series will air two nights each week, on Thursday and Friday. Last year's run had nine episodes but the BBC has realised it's on to a winner and added one to make 10. Each will be directly followed by spin-off show Celebrity Traitors: Uncloaked, the "vizpod" (visualised podcast) helmed by comedian Ed Gamble.

5. The bookies' favourites

McNally and Ramsey are bookies' favourites to win, followed by Blunt and Sheen. Ramsey is predicted to be a strategic player, after revealing they have been playing a similar board game for the past 12 years.

Jama and Acaster are also hotly tipped. King Kenny is the rank outsider, with Rajan just behind. Your starter for 10: will he be first out?

6. The trailer clues

Two trailers have been released so far and fans have been scrutinising them for clues. Ramsey is shown suppressing a devilish smirk, suggesting they might be a Traitor. Thespy elders Sheen and Grant look as if they're relishing the action. Blunt and Jama appear equally thrilled.

Rajan gives an annoying wink at the Round Table, which could be pride before a fall. There's also eager anticipation of how Myha'la's name might be misspelt on the slates. Hart seems endearingly excited but hard man Kemp looks terrified. Perhaps he's seen the ghost of Paloma Faith.

7. The buzz from filming

The "toxically competitive" Fry says she used statistical analysis and Alan Turing's codebreaking strategies to give her an edge. Action man Kemp apparently emerges as "the Daddy" in the early stages, leading the group on their first mission.

Grant admits to being surprised by the game's "cruelty". On a more lavatorial note, Lycett confessed that he spent his entire castle stint "trying not to fart".

8. The record ratings

The debut series was a smash hit, dominating the pop cultural conversation for weeks. It averaged 14.9 million viewers, peaking at 15.4 million for the final. This made it the year's most-watched show and the top-rated entertainment programme since 2016. Can the follow-up hit the same heights?

9. The juicy gossip

An intriguing rumour is that a third of the contestants, ie seven, end up as Traitors, presumably meaning plenty of recruitment to the turret. Gamble promises a "wildly different game", while Ed Havard, the BBC's director of entertainment, says: "Things happen that you didn't think could happen on Traitors and have never seen before."

The Guardian's own Marina Hyde has promised "some real meltdowns – mainly from the men". Osman added that it's "intense", while tabloids have teased "an epic sequel", full of "plot twists and paranoia".

Celebrities have also been complaining about their official headshots. Beckett wrote on Instagram: "I think there's a Traitor in the Photoshop department. What the fuck has happened to my face?" Jama was quick to reply, adding: "They did us all dirty tbh."

10. The fan theories

There's been speculation that showrunners want the Faithful to win. After all, Traitors have triumphed in the last two UK series – Carr in the celebrity spin-off, Stephen Libby and Rachel Duffy in this year's civilian edition. Does this mean producers will tip the game to favour the Faithful?

This year's extensive cohort of comedians have grumbled that the "Alan Carr factor" means they will automatically be mistrusted, making it harder for them to win. Some have taken this to mean none of Hart, McNally, Beckett, Lycett, Acaster nor Ranganathan survive until the later stages.

However, McNally let slip on her podcast that she knows who wins. Only players who get close to the endgame know this, hinting that McNally is among them.

The Celebrity Traitors is on BBC One on 1