A chance encounter with a former teacher is the fuel behind Stephen Poliakoff’s haunting and witty show

The idea of school assemblies being many children’s first experience of theatre is crucial to writer and director Stephen Poliakoff’s first stage play in 12 years.

A haunting, distinctive and mordantly witty piece of writing, My City explores the many hidden depths beneath the surface of London and the equally mysterious lives of teachers outside the classroom.

The past and present come together when city yuppie Richard (Tom Riley) discovers his primary school headmistress Miss Lambert, whose patience and flair for storytelling helped him to overcome his learning difficulties, sprawled on a bench outside St Paul’s Cathedral. This elegant woman is no vagrant, but a compulsive night-time wanderer of London’s streets.

This chance meeting leads to Richard and Julie (an endearingly blunt Si�n Brooke), his former partner in special needs, being inducted into a bizarre coven led by retired teachers in a subterranean wine bar.

In these surroundings, Miss Lambert’s stories take a macabre turn, with historical flights of fancy replaced by urban legends of ghosts and teenage killers.

The eerie nocturnal world is wonderfully realised: Lez Brotherston’s designs evoke grandeur and dinginess, accompanied by creative sound design and splendidly murky lighting. It takes a few minutes to re-acclimatise to the house lights afterwards.

Tracey Ullman is fascinatingly serene with a touch of witchiness as the mystifying Miss Lambert. As her fellow teachers Sorcha Cusack shows touching devotion and David Troughton as suitcase-clutching Mr Minken delivers an extraordinary piece of storytelling at its most powerful and heartbreaking in recounting his Jewish father’s escape from Nazi-occupied Austria.

* My City is showing at the Almeida Theatre until Saturday, November 5.