Secret Knowledge

Lars Tharp appeals to the nation to help him recover a rare piece of long-lost William Hogarth memorabilia - a precious terracotta sculpture of the artist's beloved pet pug.

Architect Zaha Hadid considers the influence of Russian abstract artist Kazimir Malevich's avant-garde art on her own avant-garde architecture.

Travel-writer Robert MacFarlane presents a documentary telling the story of Scottish poet and novelist Nan Shepherd and her book, The Living Mountain.