Great Canadian Railway Journeys, BBC2, 6.30pm

MICHAEL Portillo begins a new journey along the tracks of the Ocean line as he explores Canada’s maritime provinces en route to Quebec City using an 1899 Appleton’s guide. He begins in the Atlantic port of Halifax, Nova Scotia, where he visits an 18th-century British hilltop citadel and also learns of a catastrophic explosion in the harbour in 1917 which killed 2000 people and left 25,000 homeless.

Prison, C4, 9pm

THE first two episodes of this documentary offered an eye-opening look at life behind bars. The delayed third instalment is set to be just as fascinating, as cameras return to HMP Durham for a seven-month stretch, examining life for both the prisoners and the officers. The relationship between them takes centre stage in the opening episode, as the documentary explores the violence among prisoners and against staff. Is this just the reality of life inside or can more be done to break the cycle?

Silent Witness, BBC1, 9pm

AFTER a teenage boy is killed in a meth lab explosion, his headteacher Noah Taylor resolves to confront the drug dealers preying on locals. Dangerous batches of new drugs are hitting the streets and the effects are evident to Nikki, Jack, Clarissa and Thomas as they deal with the rise in both violent and accidental deaths linked to the narcotics, while tragedy strikes at the heart of the Taylor family. Crime drama, with guest stars Colin Salmon and Samantha Womack.

Icons, BBC2, 11.15pm

CHRIS Packham assesses the legacies and achievements of Marie Curie, Albert Einstein, Alan Turing and Tu Youyou – four of the 20th century’s greatest scientists. Curie was one of the first to examine the subatomic world, while Einstein was a physicist who rewrote the rules of the universe. Turing’s mathematical models were the forerunners of modern computers, while Tu Youyou worked on a secret project to search for a cure for malaria.