TV tonight: Alice Roberts goes on a quest to find the holy grail

Lost Grail With Alice Roberts

9pm, Sky History
Alice Roberts, professor of public engagement in science, tries to solve the 2,000-year-old mystery of the holy grail - and asks if the relic was really brought to Britain. Her whopping adventure begins on the Isle of Wight, before she works her way to Rosslyn Chapel in Scotland, which appeared in The Da Vinci Code book and film. In her quest, she investigates the legends of Joseph of Arimathea, King Arthur and the Knights Templar, and discovers an extraordinary artefact. Hollie Richardson

Inside the Factory

8pm, BBC One
Lawnmowers get the spotlight treatment in Paddy and Cherry’s last factory trip of the series. Paddy – who, shamefully, has a lawn of artificial grass – heads to Hertfordshire to see how Hayter have been making the machines since the 1940s. Cherry, meanwhile, helps to prepare the Wembley pitch for the FA Cup final. HR

Bargain Holiday Secrets

8pm, Channel 4
Remember when you could have a cheap holiday? A team of travel industry insiders think you can still manage it, reeling off tips and tricks for bringing the cost of your break down. For the first episode, they’re focusing on cruises: when to book; where and when to go; and how to slash the cost of your cabin. Alexi Duggins

Sin City: The Real Las Vegas

An alarming number of face tattoos … Tir Dhondy, right, interviews residents in Sin City: The Real Las Vegas. Photograph: BBC/Northern Child

10.15pm, BBC Three
The US entertainment capital is changing, with blackjack tables giving way to live sports betting and pool parties. But what about the residents who live in the hangover of such hedonism? In this two-parter, Tir Dhondy meets enthusiastic party promoters, exhausted paramedics and an alarming number of face tattoos. Ellen E Jones

The Good Ship Murder

9pm, Channel 5
When swaggering alpha-type Dominic is found dead in Valletta, Malta, suspicion falls on just about everybody, including his ambitious younger brother Christopher and Dominic’s longsuffering wife, Rosie. Meanwhile, back on the ship, Kate is forced to take the wheel, amid secrets that threaten to shatter her relationship with Jack. Ali Catterall

Trying

10.40pm, BBC One
The second series of Rafe Spall and Esther Smith’s lovely adoption sitcom arrives. Nikki and Jason are ready to adopt – but they haven’t had “the chat” about their preferred gender. And is reconciliation on the cards for Erica and Freddy? HR

Film choice

Along the lines of David Fincher’s Zodiac … The Night of the 12th. Photograph: Haut et Court

The Night of the 12th, 1.35am, Film4
An onscreen note at the start of Dominik Moll’s immersive true-crime drama reveals that it’s based on an unsolved murder, so don’t expect any shock unmasking at the end. This is more along the lines of David Fincher’s Zodiac, as the hunt for the killer of Clara, a young woman from a small town in the French Alps, oscillates between revelation and frustration. Bastien Bouillon plays the newly appointed lead detective, Yohan, who struggles to make progress in the case as every one of Clara’s loathsome lovers provokes suspicion. Simon Wardell

Live sport

EFL Cup football: Arsenal v Chelsea, 7.30pm, ITV1 The semi-final second-leg tie. Man City v Newcastle is on Wednesday at 7.30pm on Sky Sports Main Event.