J. Edgar and W.E: No life in this body of evidence (both 15)

Clint Eastwood's J. Edgar is a portrait of the ultimate bureaucrat. John Edgar Hoover, head of the Federal Bureau of Investigation for nearly 50 years, made it his business to know everybody else's business, by hook or (more often) by crook.

His story hinges on a major irony: the man who raided others' privacy, to the point of eavesdropping on the Kennedys and sending anonymous crank mail to Martin Luther King, was terrified of letting slip his own secret life. As scripted by Dustin Lance Black, an Oscar-winner for Milk, Hoover was a repressed homosexual who took to heart his adored mother's warning – "I'd rather have a dead son than a daffodil for a son" – yet managed to brazen out a lifelong companionship with his second-in-command, Clyde Tolson. Truman Capote called the pair "Johnny and Clyde".

It sounds like a juicily conflicted life, and yet it makes for a deadly drama. Eastwood hopscotches back and forth through time, between Hoover's rise to prominence in the 1930s and his twilight reign in the 1960s, but for all its fairness – Hoover pioneered fingerprinting as a forensic technique – the directorial viewpoint remains oddly neutral. Leonardo DiCaprio in the title role struggles with the noncommittal attitude, unsure whether to play self-tormented or to go for the full-blown monster of legend. Our first sight of Hoover as an old man, caked in prosthetics with the bulge-eyed look of a constipated frog, takes some getting used to, as does the quavery bad-actor voice that narrates throughout.

The virulent anti-communism and control-freak tendencies are always to the fore; what's missing is that spark of manipulative cunning that made his name so feared in mid-century America. Nothing Hoover does here feels truly surprising, or almost nothing. I knew that he was inclined to dress in women's clothes – I didn't realise they were his mother's. (Like Norman Bates in Psycho; some reckon the resemblance didn't end there.)

It is incendiary material of a sort, though to non-American audiences its appeal will be limited: who needs a 137-minute study of a desk job? Eastwood and his cinematographer, Tom Stern, shoot it in austere brown tones, and bury it in shadow to emphasise the dark arts Hoover made his obsession. The film dabbles in self-justification, with the boss reciting his memoirs to various Boswellian amanuenses and gilding his own crimebuster past in the process. And still the material never comes to life, marooned somewhere between myth and gossip (did he really fire an employee because he disliked his moustache?).

Two performances catch the eye amid the lugubrious duns and blues. Naomi Watts is excellent in the early scenes as Helen Gandy, the watchful woman who turned down Hoover's marriage proposal, and instead became his loyal secretary and chief keeper of secrets. Armie Hammer is touching as the not-so-straight-arrow Clyde Tolson, urbane, sensitive and quietly adoring of the man whose love would dare not speak its name. Let down by the make-up department, which turns his liver-spotted dotage into a Borg from Star Trek, Hammer still conveys a strong pathos in the final stretch.

Where Eastwood's Mandela biopic, Invictus, was too much in awe of its subject, J. Edgar feels too guarded and selective. No attempt is made to explain why Hoover failed to tackle organised crime. The boss, running to fat, is twice assured that he's only carrying "solid weight", which fairly describes the film. It just squats there, heavy and implacable, filling the screen without convincing us it has any vital message to impart.

Another infamous American is at the centre of W.E., Madonna's vanity-project valentine to Wallis Simpson, the divorcee who sparked a constitutional crisis in 1936 after she ensnared the heart of Edward VIII. The script's line is that the lady was more sinned against than sinning, that contrary to the official version she was helpless to resist the besotted royal. Ignore the couple's blithe espousal of the Nazis – the film certainly does – and you have a scandalous romance for the ages, distinguished in part by Andrea Riseborough's admirable turn as the social-climbing Wallis, poised in the regal presence when most were scared stiff. James D'Arcy isn't so assured as the king, wearing the dandy-ish duds pretty well but not quite the air of the spoilt playboy.

What drives the movie over the cliff is Madonna's nutty decision to interleave the Wallis-Edward crisis with the fictional story of Wally Winthrop (Abbie Cornish), a socialite unhappily married in 1998 Manhattan and injecting herself with fertility drugs. Wally keeps visiting the Sotheby auction of Wallis's personal treasures, poring over clothes, trinkets and furnishings like some fetishist stalker. Later, she communes with the ghost of Wallis as she wonders what it might be like for a man to sacrifice himself for love. As if that weren't enough, a security guard named Evgeny (Oscar Isaac) allows Wally to roam free through the sale exhibits after-hours and revel in the fabulousness of her heroine's taste. It transpires that Evgeny is a widower, pianist and good guy who lives in an enormous cool loft: possibly Madonna doesn't know that most people can't afford vast apartments in Manhattan, least of all low-paid menials.

The two stories don't resonate or comment on each other, they're just mashed together, boringly, fatuously. There may be an unacknowledged layer of meaning in the title, W.E. referring to Wallis and Edward's twinned destinies but also hinting at Madonna's identification (WE two) with a sexy and supposedly misunderstood American interloper. She's welcome to think that. It only becomes a problem when she tries to impose her own warped reading of history, such as the scene where Wallis dances with a Masai tribesman to the Sex Pistols' "Pretty Vacant". Did she think this was a great joke? A daring anachronism? I fear she has only made herself look a bit of a wally.