What do you do if you want your charming little island off the coast of New England to become the next Martha’s Vineyard, but it’s full of legends about local cannibalism, sea hags, clown killers, poison fog and boogeymen who slaughter teenage girls in their beds? And what if it is full of sea hags, poisoned fog and clown killers, which doesn’t bode well for the mythical status of the cannibalism and boogeyman tales?

Such is the dilemma posed by Widow’s Bay for its mayor, Tom Loftis (Matthew Rhys), in a 10-part series that in the very best way defies categorisation. Horror may be its most obvious element, but it is so much more than that. Still, for fans of that genre, the writer-creator Katie Dippold and Hiro Murai, the director of the first five episodes, which set the tone, deliver the goods, lovingly covering most of the tropes.

An alcoholic fisherman, Wyck (Stephen Root), plays the Cassandra figure: his warnings about the island’s curse are initially ignored by Tom, a longtime sceptic. There is a dark alley full of horrors. There is a hotel room in which time passes differently, outside the door of which screams of terror cannot be heard. There is no wifi and spotty phone reception, but flickering lights aplenty and power failures at all the right (which is to say, for the beleaguered islanders, wrong) moments. There are scratches that won’t stop bleeding, coma patients who turn into zombies, chained church bells tolling and – uh-oh – more fog rolling in! Jump scares and gore are measured out beautifully, too.

But Widow’s Bay is also a comedy, somewhere between workplace and family. Tom must deal with assorted local eccentrics, plus the incompetents who form his mayoral team. The fact that Kate O’Flynn has been cast as Tom’s chief assistant, Patricia, in a part that perfectly fits her talents – a glorious combination of deadpan expression with a borderline unhinged aura that always delivers great things – is the sign that we are in the presence of people who know what they are doing, that they are about to do it really well and that the result will be original and offbeat.

The casting directors need further praise for their choice of Rhys. He is known for his sterling work in dramatic TV roles, from his turn as the Soviet spy Philip Jennings deep undercover in The Americans to his unforgettable sleaze-predator in an infamous episode of Lena Dunham’s Girls, as well as his recent outing as the mesmerising wife-murder suspect in The Beast in Me; he’s always exceptional. But here he pivots with gorgeous ease from terror to comedy (and there are actual laugh-out-loud moments in Widow’s Bay) to “real” stuff – grief-tinted scenes about losing his wife, heartfelt scenes with Tom’s recalcitrant teenage son.

(Must there always be a recalcitrant teen? It’s my only criticism and it’s not even that – it’s a whiny complaint. But in a show as intoxicatingly fresh as this, a puff of stale air coming in is noticeable.)

There are great, psychologically astute moments between Tom and other characters, too, especially Wyck. It’s is Wyck who remembers the mayor best as the boy who came to visit his islander dad every summer after Tom’s parents divorced. He’s also the only one who knows that Tom just pretended to ring people’s doorbells during games of what I would call Knock Down Ginger. He has Tom pegged as a coward. Their deepening relationship as the question of whether the child is father of the man comes to the fore is worth the price of admission alone.

To horror and comedy, then, we must add small-town drama. The local eccentrics and the useless employees are not there for colour: they are full-blooded characters and they are the community. They have their troubles and their joys as well as their oddities and idiosyncrasies. Patricia is a study in awkwardness and loneliness, both of which are made worse by her ostracism over the years by the girls – now women – she went to high school with. They think she lied for attention about being approached by the man who killed several of their friends. There are many ways, Widow’s Bay suggests, to be haunted – and many ways for evil to creep through a community. Like the best horror, it suggests that the supernatural may be the least of it.

In short, Widow’s Peak is rich and wonderful. Grownup, funny, scary, true – Mare of Easttown meets Schitt’s Creek, but with something else that makes it singular. Come on in. The water’s infested with sea hags, but lovely.