Directed by Ol Parker. Starring Dakota Fanning, Jeremy Irvine, Olivia Williams, Paddy Considine 15A cert, general release, 105 min

Bring a whole lot of tissues for this powerfully manipulative tale of a British teenager dying beautifully, weeps DONALD CLARKE

HERE’S A question. If a film has the capacity to make you blub like a baby – and I mean wail noisily until you put yourself in danger of dehydration – does that mean you have to rate it as a work of quality? After all, you could get the same effect by poking yourself in the abdomen with a sharpened screwdriver.

It would have to be a very sharp screwdriver indeed to emulate the effect of Now Is Good on the tear ducts. Adapted from Jenny Downham’s novel Before I Die, the picture stars Dakota Fanning as a Brighton teenager facing up to the terminal stages of leukaemia.

Behaving in the kind of mildly disreputable manner that causes the Daily Mail to fulminate about so much young-adult fiction, Fanning’s Tessa draws up a list of things she’d like to accomplish before dying: shoplift, have sex, take drugs, other naughty stuff. Along the way, she manages to fall for a neighbour in the dishy shape of Jeremy Irvine.

The beautiful-person-dying-beautifully genre is, perhaps, the most suspect in the cinematic arsenal. Anybody who has been close to somebody – particularly a young person – who has passed away slowly will recoil from efforts to sentimentalise a terminal condition.

Now Is Good treads the line between schmaltz and realism with some caution. The film does dare to touch on the condition’s harrowing symptoms: a massive haemorrhage is depicted in gruesome detail. It allows its doomed heroine to be selfish as well as brave. But the picture gives in to a kind of hazy new-age take on the passage from experience to oblivion. We never quite come to grips with fear.

It is, however, hard to complain about a drama that is so brilliantly manipulative in its manoeuvrings (this may sound like an insult, but how else would one expect a weepie to behave?). Fanning is convincingly English and believably fragile in the leading role. Paddy Considine seems hollowed out as a father who can’t decide whether to be devastated or furious. Ol Parker, workmanlike director of Imagine Me You, brings a light, unshowy touch to the accumulating misery.

Is Now Is Good a great film? Almost certainly not. But its effectiveness is frightening. Bring whole sheaves of tissues.