Looking to fill a blank space in the September 1997 edition of Backwoods Home Magazine, employee John Silveira wrote a pithy classified ad as a joke.

The ad stated: “Wanted: Somebody to go back in time with me. This is not a joke. P.O. Box 91 Ocean View, WA 99393. You’ll get paid after we get back. Must bring your own weapons. Safety not guaranteed. I have only done this once before”.

Little did Silveira know that his throwaway paragraph would prove the inspiration for the low-budget Safety Not Guaranteed, a comedy-drama equal parts whimsical and melancholic from the mumblecore stable of American independents.

Disconnected and disillusioned Darius (Aubrey Plaza) interns at a Seattle magazine and volunteers with fellow staffer Arnau (Karan Soni) to assist writer Jeff (Jake Johnson) in tracking down the ad’s author in a sleepy seaside town. This turns out to be Kenneth (mumblecore alumnus Mark Duplass), an eccentric and paranoid supermarket employee who deals in conspiracy theories and is convinced secret agents are out to get him.

She poses as an applicant with her own reasons to want to travel back in time and wins the trust of the slightly obsessed, but kind-hearted loner, who sees in Darius a kindred spirit and someone who’s not afraid “to stare fear and danger in the eye and say ‘yes'”.

Darius at first indulges the child-like Kenneth’s plan to build a time machine, believing it to be nothing more than a fantasy, but as they spend more time together she finds herself increasingly attracted to the fellow misfit and starts to wonder if what he’s claiming is actually the real deal.

Safety Not Guaranteed brings to mind the offbeat 1980 film Somewhere In Time, in which Christopher Reeve’s writer becomes so obsessed with a picture of an actress (played by Jane Seymour) that he travels back in time to 1912 to be with her.

Memory, in particular the desire to recapture and revisit a specific moment in time, is a prominent motif throughout the film. Darius, who has resigned herself to simply “expect the worst and try not to get my hopes up”, would rather return to when life was easier and made more sense.

According to Kenneth, the whole point of building his time machine is to prevent a tragic event from occurring, although as he lets slip to Darius, it’s actually more “about a time and a place” when he believes he was happiest.

The melancholic yearning for younger, less complicated days is also present in the character of Jeff, who uses the assignment to look up his first love, whom he has reminisced about and wondered ‘what if?’ for years. He also urges Arnau not to waste his youth and, in scenes reminiscent of Roger Dodger prises the young intern away from his laptop to introduce him to the world of girls.

Director Colin Trevorrow gives the film a lightness of touch that dilutes the sadness of Derek Connolly’s script. Duplass, who has made a career out of directing inward-looking adults with arrested development excels as Kenneth, bringing the right mix of oddball innocence to the role.

Plaza (from TV’s Parks and Recreation) has the face-slapped-with-a-wet-fish look down to a tee, but finds an endearing sweetness in her scenes with Duplass. Indeed, the moments when the two are training for their ‘mission’ are the highlights of the film.

Whether you buy the ending largely depends on how invested you are in the characters. Trevorrow for one tries his best to sell it, as do the cast, and while it doesn’t entirely convince there’s enough heart here to earn a smile come the closing credits.