Likened to the Philip K Dick-inspired 2011 sci-fi thriller The Adjustment Bureau reimagined as "an Ealing comedy" and with twisted echoes of Wim Wenders' romantic angel fantasy Wings Of Desire, the off-the-wall comedy takes place in a world where invisible immortals watch over humans and intervene in (or interfere with) their lives.
Scott Haran (Wizards Vs. Aliens) plays Pete, a new Bystander being shown the ropes by Walsh's world-weary tutor Frank, who is mostly irritated by the humans they watch. For fun, Frank suggests they swap their charges.
Also featuring comedians Nick Helm, Marek Larwood, Lauren Douglin and David Schaal, who played Jay's dad in The Inbetweeners, with Lock, Stock And Two Smoking Barrels' Frank Harper, Caroline Ginty (GameFace), Emily Milburn (Neighbours), Tom Clegg (The Outlaws) and former Page 3 girl Lucy Pinder, the film is directed by Gabriel Foster Prior.
The Bystanders asks: "Why does shit happen in life despite your best efforts?
"Well, it might just be The Bystanders, screwing with your life because they are bored. Bystanders are invisible immortals supposed to act like guardian angels. Each Bystander is tasked with watching a human, but they have been recruited from the human world and are mostly bitter people with no friends; a bunch of misfits and loners."
Having had its worldwide premiere at the Austin Film Festival in October, The Bystanders will be the closing night film of the Sci-Fi London Film Festival, screening on 6th June at the Rich Mix arts centre in Shoreditch.
Walsh previously made the 2016 Sky Arts TV movie Seann Walsh In Ireland, in which he played Robin, inexplicably visiting the Emerald Isle to detox, co-starring Irish comics Fred Cooke, Karl Spain and Peter O'Byrne, as well as Grace-Anne Kelly.
You can watch The Bystanders trailer here: