After writing stories about deranged Daleks, pitiless criminals and blood-sucking vampires, Steven Moffat’s next project is arguably even more terrifying: people you meet on holiday who get back in touch.

It was announced on Thursday that the former Doctor Who showrunner has written a play, to be directed by his regular collaborator Mark Gatiss as part of Chichester Festival theatre’s 2020 season.

Moffat said he got the idea from the experience of friends who went on holiday, met someone, exchanged emails and “then thought: ‘Jesus, they’re coming to stay!’ They soon find out stuff they’d rather not know. I said: ‘Can I have that? Can I take that story and reorganise it so that it goes even more badly than it did in real life?’”

His ambition while writing the play was simple: “I wanted to avoid any controversy and just write a silly, funny comedy, frankly … at least I hope it’s funny.”

The Unfriend will be Moffat’s first produced play, but not the first he has written. After Doctor Who and Sherlock he wanted to try something different, so wrote a play he thought was good but few others did.

“It just didn’t excite much interest,” he said. “It was useful. I’m honestly not a terribly arrogant person but any tiny trace of arrogance that might be there because of Sherlock and Doctor Who … it was removed at that point.

“The advice I always give to young writers is if people say no, just try again. So I wrote another play.”

Facebook Twitter Pinterest Steven Moffat, left, with his regulator collaborator Mark Gatiss, who will direct the play. Photograph: Peter Byrne/PA

The Unfriend will star Reece Shearsmith and Amanda Abbington as a couple, married for 20 years, who go on a cruise as a break from their teenage children. They meet an eagerly friendly American passenger, played by Frances Barber, who later comes to stay.

It is billed as an “entertaining and satirical look at middle-class England’s disastrous instinct always to appear nice”.

The play has been announced as part of Chichester’s 2020 season, under the artistic direction of Daniel Evans, which includes five world premieres, five revivals, and two musicals: South Pacific and Stephen Sondheim’s Assassins.

As well as Moffat, the novelist Kate Mosse has written her first play – an adaptation of her Gothic mystery The Taxidermist’s Daughter, which is set locally in rural West Sussex.

There are also new plays by Suhayla El-Bushra, who has adapted Andrea Levy’s novel The Long Song, and the American playwright Christopher Shinn with The Narcissist, described as a “witty take on personal and political communication in the internet age”.

At Christmas the Chichester Festival youth theatre will present a new version of Pinocchio by the theatre’s writer-in-residence, Anna Ledwich.

The season will have a 50/50 gender balance and and 60/40 female directors, the theatre said.

One of the questions Moffat always gets asked is will Sherlock ever return to TV? “I would be astonished if it didn’t come back,” he said. “We all think it would be quite nice to rejoin them once a few years have gone by. Normally Sherlock Holmes and Dr Watson are portrayed in their 50s and we did them in their 30s. I’m not saying we’re going to wait 20 years but it would be quite nice to leave it a while.”