Lygia Pape, Serpentine Gallery, London

Lygia Pape, a neglected 20th-century revolutionary and survivor of the political hijacking of art, is given a long overdue show

From 1954 to 1956, Lygia Pape – a Brazilian, then in her mid-twenties – made a series of works in oil on wood, listed as Sem Titulo, or Untitled. The most notable thing about these is how old-fashioned they are.

If you didn't know about Pape (and it is very likely you won't), then you might guess that the works were by Malevich or Van Doesburg. They seem to date from the 1920s, although they were made a quarter of a century later.

As you look at these sort-of-Suprematist works in the Serpentine Gallery's Pape show, a little Eurocentric smile may play across your lips. How sweet that Latin Americans were making this kind of thing in the 1950s! It is an assumption that is seriously wrong.

Outside of its native Russia, the style of art broadly labelled "Constructivist" survived the 1930s. If they cannot be said to have thrived, Constructivists did make some of the most interesting, and overlooked, work of the 1950s. Marlow Moss, Mary Martin and Burgoyne Diller are not household names now, though they were revolutionary in their day. Nor is Lygia Pape, who was arguably the most subversive of all.

What separates Pape from the other three – she called herself a "Neo-Concretist" – is less that she was Brazilian than that she was 20 years younger than them. Moss, Martin and Diller all ended up at Constructivism: Pape started off there. As a creed, the movement had always faced the problem of where to go next – what to do with its architectural underpinnings, the urge to build. When Pape died in 2004 at the age of 77, she had lived long enough to answer that question.

In the late 1950s, modern Brazil was being built. Juscelino Kubitschek came to power with a promise to deliver 50 years of progress in five, the most visible outcome of which was Brasilia, designed by the communist architect, Oscar Niemeyer. It seemed a good time to be a Constructivist, and Pape reacted accordingly. The first two of her three "books" in this show – actually an installation piece with a film of its own making – date from 1959-60. Housed in a large vitrine, the folded-paper sculptures of Livro da Arquitetura bear a strong resemblance to Niemeyer's model for the planned federal capital, on show that year.

Like the new capital, and the so-called "Golden Years" it stood for, there is a darker side to Pape's work. Seen with Livro da Criação, the Super-8 movie of the artist as origamist, the Arquitetura project becomes frail and tenuous, a trick. If construction had been heroic, its heroism was now tainted. Just as Niemeyer's Brasilia would come to be seen as monolithic, so the freedoms it stood for were hollow: a coup in 1964 ushered in 21 years of military government, one of the most repressive in Brazil's history. Pape was left with a new problem. She was a Constructivist, but construction had been hijacked by a system she found repulsive.

At this point, we need to look at the drawings in the Serpentine's West Gallery. These show signs of an exposure to American modernism – Agnes Martin, Frank Stella – although, as with Pape's Suprematist works, the dates do not add up. The problem now is that they are too early: that she was doing Stella and Martin in 1955, before Stella and Martin were. Pape was a hugely innovative artist, and that was what saved her art.

From the mid-Sixties on, Pape turns herself into what you might call a Soft Constructivist. If she had found linear abstraction in the 1950s, the Sixties meant film and performance. The video monitors in the Serpentine's first room show her bringing power to the people by building cloth cubes for them to climb out of, playing maracas, or covering whole streets of happy cariocas in vast sheets of cloth. Twenty years before the historian Rozsika Parker wrote The Subversive Stitch, Pape saw the feminising power of cloth, its promise as an antidote to Niemeyer's ferroconcrete. Her work is revolutionary, but too gentle to seem it.

This paradox reaches its climax with Ttéia, in the Serpentine's central gallery. A play on the Portuguese words for "thread" and "cutey-pie", Ttéia takes the monumentalism of Constructive art and renders it fleeting and slight. Using gold threads to suggest a series of columns, Pape turns the solidity of architecture into shafts of light; a kind of hope from darkness.

To 19 Feb

Next Week:

Charles Darwent looks into the influence of Rubens, at Tate Britain

Art Choice

The Ashmolean Museum in Oxford has unveiled six new galleries, dedicated to ancient Egypt and Nubia. With coffin lids and mummies, fragments of temples and tombs, there's plenty to see at this £5m refurb. Or visit another newbie: Scotland's revamped National Portrait Gallery, displaying 3,000 works, from Robert Burns to Susan Boyle.