There’s a queasy sensation you get when watching something like K-Pax; a film that obviously fancies itself as a major blockbuster, but which came and went and barely touched the sides. It ‘s hard not to feel embarrassed on its behalf, and it doesn’t help when the feature is preceded by trailers for The Films That Sunk Film Four. It’s pretty much a two-hander between Jeff Bridges, who plays Mark Powell, a put-upon doctor in a psychiatric ward, and Kevin Spacey as Powell’s latest patient, who insists his name is Prot and that he comes from the far-away planet of the title. Although the source was a popular novel, in practice this plays like a lazy collision of second-hand Hollywood ideas – a bit of Awakenings (1990), a chunk of The Day the Earth Stood Still (1951), not to mention a dash of Mork and Mindy. Even the mystery-visitor-from-space is referenced by the presence of Bridges, who fell to Earth himself in John Carpenter’s Starman (1984). But the oldest plot in the book can sparkle in the right hands. Ian Softley quietly made a name for himself with Backbeat (1993) and The Wings of a Dove (1997). Together with a pair of dependable, likeable acting heavyweights, K-Pax should be a blast. Instead, it’s a bit of a drag.

The main problem is a leaden and prosaic tone that betrays the ambiguity of the material. At the tale’s heart is an enigma – is Prot from outer-space or isn’t he? – but rather than dancing between the two possibilities, we lurch heavily between evidence that yes, he definitely is, and no, he’s probably from somewhere near Mexico. There is little suggestion that viewers should be able to decide for themselves without being lead by the hand. Softley attempts to cook up some portentous imagery but the results are wishy-washy and underwhelming. The leads never really get the chance to go for broke, and Spacey in particular uses the opportunity of playing a maybe-alien (was he cast on the grounds of his surname?) to repeat the same kind of detached, calculated performance he has wheeled out many times before. It’s hardly effective, and it doesn’t help that he looks increasingly like an older, balding version of Peter Tork from The Monkees.

K-Pax has all the obvious mainstream hit ingredients in place – an emphasis on the importance of family, the promise of salvation, and an uncluttered time-lock narrative (Prot’s insisting on getting back off to K-Pax within the week). But in execution it feels reheated and ordinary. It’s too adult to be an E.T. (1982) for the 21st century, and yet too plain for adult viewers to really engage with. Ultimately this is harmless, leisurely viewing that should be trying to move at the speed of light.