Filmed in the UK heatwave of 2022, Last Swim takes Ziba and her group of friends through well-known spots of London such as Portobello Road, Hampstead Heath and Primrose Hill by car, bike and train.
Industry publication Screen Daily said the film was "shot, one suspects, with a touch of guerrilla ingenuity... Last Swim also has a palpably improvised component in the friends' genially pitched running banter."
The director agrees that the young cast had freedom to change the script "to make it as authentic as possible".
"I think whenever you tell a story about young characters, you need to give them a certain amount of flexibility," Nathwani says.
"If there was a more natural way of delivering a line in a language that they would more authentically use, we would then write that into the script.
"And they were very good at challenging me as well. They would challenge me about choices that I and Helen had made on the page if they didn't feel it rang true of their characters."
"This is Gen Z friendship on screen," adds Hekmat.
"Sasha says that his [Millennial] generation is the one of hard knocks and they didn't grow up with the idea that mental health needed to be considered in day to day lives," she says.
"I think a great way of seeing how connected this film is to Gen Z is just the friendship that me and the rest of the gang have together.
"They're not afraid to ask each other about their feelings and the boys aren't afraid to open up a bit more. I think it's really reflective of our friendships in the way that we are able to speak to each other."