Nick Hornby is a pleasing novelist whose film adaptations have resulted in some great, smart comedies. “About a Boy” is my favorite, and “High Fidelity” is everyone else’s favorite; both are intelligent, heartfelt and mordant enough to enjoy without feeling embarrassed. In both cases, a strong cast pulls off source material that is light enough in its original form to survive the translation intact.

So you would think that this formula would hold up in “A Long Way Down,” a film adaptation of a Nick Hornby book that stars Aaron Paul, Toni Colette, Pierce Brosnan, and the lovely but tragically named Imogen Poots as four disparate Londoners who meet on a rooftop amidst their separate suicide attempts. Out of sheer awkwardness, none of them jump but instead form an unlikely alliance to hold their lives together a little longer.

Despite a couple of strong performances, Nick Hornby’s story of four strangers with a life pact fails to engage.

Despite a couple of strong performances, Nick Hornby’s story of four strangers with a life pact fails to engage.

This is one of those hard to swallow situations that needs convincing writing to hang together. The writing, alas, was not convincing. Also, to have such a serious situation resolved in such a facile and unbelievable manner requires convincing performances. The performances were not convincing. The tone of such a tale must walk the line between sadness and comedy. It did not.

Pierce Brosnan leads the story as the narrator; he plays a formerly famous television talk show host who was disgraced and imprisoned after a sex scandal. His character was the most problematic, as he was meant to be a shallow, empty fellow who gains some depth and empathy by interacting with his fellow attempters. This would have required the emoting of some depth and/or empathy. I missed that part, but perhaps I was in the ladies’ room.

Like the movie itself, Brosnan’s character has serious tonal issues, flitting between sort of caring and then developing a plan to manipulate the media for his advantage. This also gives us the film’s most boring sideline, in which the four people, nicknamed the “Topper House Four” after their story leaks, and the concept of the media is ineffectually skewered.

The other characters make a better effort with their shabbily written characters. Aaron Paul plays a frustrated failed musician, and Poots plays a beautiful party girl with a famous family tragedy. The best actor in the film is Toni Colette, who also gets to play the only person with any real problems, a single mother caring for a severely disabled adult son.

After surviving their New Year’s Eve suicide plans, the four form what they call the Pact, swearing they will not attempt again until Valentine’s Day. Soon, because of two of the character’s fame, their story becomes known, crowds of reporters follow them around, and their pact takes on a life of its own.

Except, of course, it doesn’t. A life of its own is exactly what this slight and silly film lacks. You keep waiting for the story to dig in, but everyone just skitters over the surface. Revelations, when they are made, are lame. Characterization is willy-nilly.

And there is entirely too much fake laughing. Like, the four of them just fake laugh at inopportune times, and this is meant to signify how amazingly unlikely yet warm it all is. They take an unbelievable, inane vacation together, and fake laugh and swim, and it’s just not enough. Their lives get resolved through no effort, and the last scene is as unbelievable as the first.