Caryl Churchill's 1997 double bill is about as willfully and wonderfully slippery as they come. Revived here for its 20th anniversary by the Tobacco Factory and the Orange Tree, the two pieces – Heart's Desire and Blue Kettle – are brilliantly entertaining and entirely confounding all at once.

Heart's Desire is set in the kitchen of Brian and Alice who are waiting for their daughter's return from Australia. As the play starts, it also restarts over and over again, resetting to the beginning half way through a speech or a line. Radically different versions of the same scenario are played out – at one point (spoiler alert!) gunmen burst into the kitchen, at another a great bird stalks its way through the door. Pretty much every possibility you could think of happens. Sections are sped up, words are cut, speeches are added. It's a little like Nick Payne's Constellations but with a lot more laughs.

In Blue Kettle, Churchill again plays with form to the backdrop of an intriguing story. Here we follow Derek who seems to have tracked down his birth mother, but in actual fact is a serial adopted-mother-finder. He has five on the go. As the play progresses, the script is increasingly filled with the words blue and kettle, until you're left reading between the lines of a conversation that on paper makes absolutely no sense.

They are both very clever and gloriously silly plays and it is an absolute treat to watch them staged so well by director David Mercatali. To perform Heart's Desire is to grapple with some really sharp, tricky cues and the actors and lighting and sound designers rise to the challenge beautifully. Blue Kettle is again an impressive achievement in timing and memory for a strong team of actors, who perform the text with the playfulness it asks for.

It's never easy to explain a Churchill play and these two are characteristically oblique. But the playwright's invention and experimentation with form and her precision with language are masterful here. Mercatali wisely taps into the humour of the piece, which means that even if you come away feeling as though you had no idea what was going on, you will still have laughed. A lot.

Blue Heart runs at the Orange Tree Theatre until 19 November.