The Sky at Night team investigates the controversial world of alien communication. The search for life on other planets is one of the most fascinating subjects in science. But what is less reported is the work being done around the world to determine what happens next. If we discover aliens, how would we contact them, what should we say and should we communicate with them at all?We follow astrobiologist Doug Vakoch on a trip to the UK. Doug runs an organisation aiming to contact extraterrestrials and is here to meet with experts who can help with his mission, including Professor Arik Kershenbaum from the University of Cambridge. Arik is a zoologist who specialises in animal communication and xenolinguistics - the language of aliens. He explains how the common patterns in wolf and dolphin vocalisations can help us to form a message to send to space. Doug also meets Paul Quast, a researcher from the Beyond the Earth Foundation, who is assembling a ‘Companion Guide to Earth' for future humans and passing aliens.Exoplaneteer George Dransfield travels to the Jodrell Bank Observatory to meet astrophysicist Professor Tim O'Brien. Tim explains how scientists around the world use radioastronomy to listen for extraterrestrial signals. He demonstrates how we might identify an alien ‘technosignature' - a sign of an advanced technological civilisation from another planet.Professor Chris Lintott delves into the history of scientists trying to send messages to aliens, and he asks if we should really be trying to communicate with them at all.