UNSURPISINGLY, given its title, loneliness is the key theme running throughout Frantic Assembly’s I Think We Are Alone, a production celebrating the physical-theatre group’s 25th anniversary.

And it’s a relentlessly mean and depressing world which is its focus. Cabbie Graham is dealing with the news that his wife Bex is dying of cancer while Josie, struggling to mourn the loss of her dad and her beloved dog Queenie, is desperately missing her son Manny — one of the few state-educated black students studying at Cambridge University.

Estranged sisters Clare and Ange can’t bring themselves to talk to each other because they’re both hiding the same dark and disturbing secret about their past which, despite their efforts, they can’t suppress.