Mel Giedroyc is tunnelling into the world of engineering, asking how we build and operate trains under some of the world’s busiest cities? Mel has found a new best friend in, Isabel Coman, Director of Engineering at Transport for London, who is here to guide her through the particulars of subterranean transport systems.

Deborah Meaden, entrepreneur and investor, is delving into the emotional lives of animals - do our furry, feathered, and scaly companions have feelings like grief in the way we do? Helping her to sniff out the science of animal emotions is Dr Liz Paul, a comparative psychologist from the University of Bristol.

Comedian Nish Kumar wants to know - are we totally screwed when it comes to climate change, or is there still hope? Helping him unpack tipping points, rising temperatures, and how we might turn the tide is climate scientist Ed Hawkins from the University of Reading.

Series Producer: Melanie Brown

Assistant Producer: Olivia Jani

Executive Producer: Alexandra Feachem

BBC Studios Audio Production