The Trial of the Chicago 7

There's a spring in the step of Aaron Sorkin's dramatisation of events that unfolded around the Democratic Convention in 1968 - and a message about protest, prejudice and attitudes that remains sharply relevant today. His script bounces along whether inside court or out and while he no doubt applies a certain Hollywood gloss to proceedings - unlike the similarly themed, more seriously handled Mangrove - the result is informative and compelling and served up with sufficient verve so that you don't feel as though you've sat through a history lesson by the end of it.

All of which is not to say that there isn't plenty of detail contained in this story of how the group of the title came to find themselves in the dock. Sorkin starts outside the courtroom, applying a judicious amount of archive footage alongside dramatisation to set the scene of how a disparate group of protesters came to be in Chicago in the first place.

There's the chaotic energy of the yippies, of course, represented by Abbie Hoffman (Sacha Baron Cohen) and Jerry Rubin (Jeremy Strong), but also young preppy types Rennie Davies (Alex Sharp) and Tom Hayden (Eddie Redmayne), who are focused on protesting the war, and middle-aged pacifist family guy David Dellinger (John Carroll Lynch). Alongside them - although little more than set dressing - are John Froines (Danny Flaherty) and Lee Weiner (Noah Robbins), plus the "eighth" original indictee Black Panther Bobby Seale (Yahya Abdul-Mateen II) - whose case was ultimately declared a mistrial for reasons that become abundantly clear during the course of this film.

The intended peaceful protests went south, and in quite a few other directions, but it required a certain period of time in the prosecutorial kitchen to cook up conspiracy charges against the men. There's no doubt Sorkin's direction is better the more confined it is, while he's able to handle large central casts well, he seems less sure when he has a host of extras, so that the crowd scenes border on being too orderly, although the archive footage helps a lot when it comes to giving us a feel of the day. Once he's behind closed doors, however, Sorkin comes into his own and the tensions mount. There's the disparity between the cocksure comedian Hoffman and his more chilled out side-kick Rubin and the clean-cut Hayden and Davies. Then there's the contrast between the accused and the bordering-on-unhinged judge Julius Hoffman - no relation - played by a scene-stealing Frank Langella, who dances between bureaucratic acidity and borderline insanity with the care of an acrobat on a ledge. Slotting neatly between these worlds is the men's attorney William Knutsler (Mark Rylance, pitching in just the right level of consternation at proceedings) and prosecutor Richard Schultz (Joseph Gordon-Levitt).

You could gripe about Cohen's vowels, which stray away from American to British shores quite frequently, but as his Borat films prove, he's so magnetic he somehow gets away with it, with Sorkin applying a clever structural device of having Hoffman tell his story as stand-up to help the history flow. Balancing this amount of core cast isn't easy but Sorkin keeps the plates spinning and even finds time to add a few flourishes - including Michael Keaton as ex-Attorney General Ramsey Clark in a couple of riveting scenes. This is a clean-cut, old school script that has no time for messy interludes or spare chat, but this is a feature film not a documentary and the polish adds pace.