Tom Hiddleston says it "felt very wild" playing the pastor of a village terrified by a mythical sea creature, in Apple TV's The Essex Serpent.
Set in Victorian coastal Essex and London, the series is based on Sarah Perry's award-winning book, and co-stars Homeland's Claire Danes.
Hiddleston's character, Will Ransome, tries to quell locals' fears, telling them the creature is "an invention, a symptom of the times we live in".
Danes plays London widow Cora Seabourne, who goes to the village to investigate reports of the serpent, after an earthquake dislodged fossils in the Essex landscape.
This causes the God-fearing locals to wonder else might have been awakened.
Rumours of a malevolent sea monster escalate after a local girl goes missing and is presumed dead. Some villagers work themselves into a frenzy, saying she was "taken for her sins by the Blackwater beast".
Describing the scripts as "brilliant", Hiddleston tells the BBC: "They were about complex people at a complex time, with a conflict of ideas."
He said making the series "felt very wild, and mirrored the passions of the story we were telling. I was really excited to do it".
'We like to be humbled'
Hiddleston is of course no stranger to monsters, having been on the receiving end of "Hulk-smash", as Loki in the Marvel films.
He thinks a seemingly endless fascination with mythical creatures is part of our need to account for things we don't understand.
"Monsters are symbols of mystery... they reflect our need to find meaning in our lives," he muses.
"I think human beings need, or are drawn, to externalise mystery. We like to be humbled by forces in nature and in our world that seem to be unexplained."
Given it's "probable we know we don't know everything", he thinks "we still have so many questions".
"And sometimes those questions coalesce into the shape of monsters, benign and otherwise."
His character Will's views are challenged by Cora, who he meets in the swirling coastal mists. Much of the plot centres around the tensions - both intellectual and sexual - between them.
The story's focus may be the serpent, but it pivots around Danes' charismatic Cora, going it alone with her young son after the death of her brutal husband.
But unlike many other period TV dramas, Cora is not looking for a new spouse.
"No. Oopsy daisy," laughs Danes, clearly delighted at her character's independence.
"Her intellectual pursuits are the driving force," she adds.
Cora shuns religion and is passionate about fossils. She is desperate to discover if the serpent is a dinosaur which escaped extinction.
"I think it's her eagerness to realise herself," she continues. "Her development had been quite arrested when she married this intensely controlling, abusive man.
"She's just so relieved to have a chance to breathe again."
Prof Gowan Dawson, from University of Leicester's Victorian Studies Centre, told the BBC some of that era's most notable women "who collected and studied fossils did not marry, and devoted their lives to their palaeontological pursuits".
"This was the case with both Mary Anning and Elizabeth Philpot, who, despite their very different social backgrounds, worked together in Lyme Regis, and made some remarkable discoveries of fossilised sea creatures," he said.
"Fossils opened a window on a mysterious past populated by dragons and monsters, when Victorian Britain was otherwise focused on forging a new industrial future."
It has to be said that although the wild Essex seascape explored by Cora looks stunning, it also looks inescapably cold and damp.
"My long, high-tech underwear was heaven-sent - effective and very, very welcome," she says, grimacing slightly at the memory of being so chilly.
Clemence Poesy, who plays the pastor's wife Stella, adds she was saved by "some very elaborate, nude-coloured stuff, almost like wetsuits" under her dresses.
Poesy, who also features in an episode of Amazon Prime's new comedy Ten Percent, says her character is "quietly extraordinary" and a much smaller presence than Cora.
The talk of monsters resonates with her too, not least because her five-and-a-half year-old is pretty obsessed with them.
"It is a thing isn't it?" she says with a laugh.
The actress also thinks the storyline about doubt, science and belief resonates with modern-day life, comparing it with some people denying the existence of Covid.
"It just felt like science about coronavirus was sometimes denied without any kind of evidence," she says.
"I think there's a space online that allows superstitions or myths or things to just kind of grow in a way that they probably didn't before. Because we were filming this in the middle of a pandemic, it felt quite accurate."
The book and TV series are very much about a clash between science, religion and mythology. But Hiddleston's character thinks religion offers more peace of mind than science, and that without faith, people will invent evil creatures.
The scientific developments of the day are seen in London, featuring some undeniably gory medical scenes.
Fear the Walking Dead actor Frank Dillane plays Luke Garrett, a young doctor pushing boundaries by performing open heart surgery.
"I think the Victorians were incredibly forward-thinking - it was a time of massive advancements in science, architecture, philosophy and religion," he says.
"I think that we have this misconception of them being stuffy, but actually they weren't."
He says it was "a lot of fun" researching his part, and he learned "Victorian hospitals were not the nicest places in the world, they were often called death houses".
"Often if you went in, you weren't coming out," he adds.
"Surgeons back then were often referred to as glorified butchers - there would be gangs roaming London, killing people and selling them on to surgeons, or digging up corpses to operate on."
He also discovered that "surgeons were basically people with knives, and 50 years prior to this, they would be butchers or hairdressers".
Describing the "red and blue swirling thing" outside a hairdresser or barber's shop, he says: "Well that was because back then, if hairdressers also did surgery, you would tie your bloody rags around the light outside, so people knew - they cut hair, but they'll also cut you up if you need it."
His surgical scenes were done with the help of an on-set surgeon, and Dillane adds: "There were prosthetic rubber bodies and people in the background squeezing hearts."
The driving force behind the series was director Clio Barnard, who has been nominated for Baftas for her films including 2013's The Selfish Giant and this year's Ali & Ava.
Hiddleston says he received the scripts "with a beautiful letter attached" from Barnard, who he had "admired for a long time".
Dillane adds: "Clio was a big draw for me. I thought it was a great opportunity to work with a brilliant director."
Hiddleston adds that despite all the conflicts in the story, he found the connection between Will and Cora "very optimistic".
"One of my favourite scenes is a conversation that we have on a beach, when Cora says, 'science requires dreams just like your theology. You have to make a leap in the dark from ignorance to understanding'.
"And Will simply replies, 'faith'."
Hiddleston goes on: "The resonant thing for me I think is - maybe it's just getting older - how do we feel that our brief, brief time on this planet has meaning?
"And so the curiosity I am inspired by is to keep thinking, keep listening and stay open-minded. You never know where the inspiration is going to come from."
The Essex Serpent is on Apple TV+ from 13 May 2022.