In Gary Ross’ 1998 comic fantasy Pleasantville, two squabbling siblings are thrown into a 1950s television series where they are trapped with an array of old-fashioned parents, schoolmates, and other residents. While attempting to find a way back out to the real world, their 1990s habits and conventions begin to have a seismic effect on those around them.

Writer/director Gary Ross hits on a great premise with Pleasantville – effectively a reverse variation on Woody Allen’s The Purple Rose of Cairo (1985). That film featured a matinee idol walking off the cinema screen to the real world; Ross simply pushes in the other direction. By an odd coincidence, actor Jeff Daniels appears in both.

The film’s first half works delightfully well. For one thing it is brilliantly cast. Tobey Maguire and Reese Witherspoon are pitch-perfect as bickering siblings living in 1990s America, and Maguire’s earnest adoration of 1950s television is well balanced by Witherspoon’s aggressively destructive attitude to their situation. Once trapped within the Pleasantville TV show, they are faced with superbly performed TV parents courtesy of William H. Macy (more effective casting in a Hollywood movie than this is honestly rare) and Joan Allen. Ross’ screenplay keeps things light and entertaining as the 1990s effect of Maguire and Witherspoon’s characters gradually begins to disrupt the fictional world around them – culiminating in a burst of colour via a burning tree. It is the film’s finest moment.

Jeff Daniels is particularly strong as Bill, a soda fountain owner who begins to question his own reality when it begins to crumble around the edges. It is a very gentle performance, driven more by a meek curiosity than any sense of rising dread, and gives the film an emotional core. Also strong is the late J.T. Walsh, ever-reliable as the town’s no-nonsense and fearful mayor.

If things held steady at this level of confection, Pleasantville could be a wonderfully breezy and enjoyable blend of comedy and fantasy. Instead Ross aims for a deeper profundity, and in doing so shatters the film’s second half with a ham-fisted and poorly judged exercise in social commentary. He uses the growth of colour across the town as a blunt analogue for bigotry and social justice, with monochrome citizens turning against their freshly colour neighbours and introducing a growing number of restrictions on their lives. It is a very loose and ill-defined sort of bigotry that rolls in hints of conservatism, homophobia, racism, and McCarthyism. When characters begin to refer to “coloured people” in a film with exactly zero actual people of colour in the entire work, Ross’ allegory shifts from weak to active inappropriate. It all culminates in a dreadful courtroom climax in which all of Pleasantville’s problems are solved by a chipper attitude and a cloyingly awful speech by Maguire.

It is always a shame when a strong set-up leads to such a poorly articulated third act. Both heavy-handed and superficial, the film does not even manage to wind things up in an effective or enjoyable way. Such a strong beginning. Such a terrible waste of time and talent.