Filmed onboard the aircraft carrier HMS Illustrious, this observational documentary series follows the professional and personal lives of the ship’s crew as they embark on a four-month deployment, travelling thousands of miles from home. In this episode, the sailors are put through their paces in a battle-readiness inspection; and the ship finally leaves British waters.

The mighty Illustrious aircraft carrier is about to set sail on a four-month deployment. With a crew of 1,000, this 22,000-ton floating city – nicknamed ‘Lusty’ – is home to all manner of sailors, from stewards to engineers, officers to deckhands. The ship’s projected route will take it through the Strait of Gibraltar, across the Mediterranean and through the Suez Canal to the Indian Ocean, where it will support Harrier jump jets serving in Afghanistan. So far, things have not gone according to plan. It is day 21 of the deployment and Illustrious should be in Malta, but a failed inspection and technical difficulties have kept her in Portland, Dorset.

Despite the setbacks, however, life onboard ship goes on as normal. As the mail arrives, the post bags are particularly bulging since today is Valentine’s Day. A number of the crew members receive packages from home, while 19-year-old Rachel Wright has made her own card for chef Russell – despite already having a boyfriend.

One person who will not be receiving a card is weapon technician Jason Farnsworth, who symbolically shreds the last remaining photograph of his ex-girlfriend. “It was a bit difficult because I’m always away,” he says of his former relationship. “I just had to end it with her.” But he does not seem too upset by the breakup. “I’ve already got a bird lined up anyway,” he muses, philosophically.

Love is the last thing on the minds of Illustrious’s marine engineers who have had to work around the clock to fix the ship’s technical problems. One of the huge prop shafts, which connect the ship’s engines to the propellers, has developed a worrying screech and must be repaired. After a night of hard work under the watchful eye of senior marine engineer Helen Ashworth, Lusty is given a clean bill of health and can finally leave Portland. However, there is no time to celebrate as the ship and her crew head straight for a naval exercise area off the Dorset coast for a comprehensive battle-readiness test.

A few days before the inspection, everyone onboard throws themselves into preparing the ship, including the officers. To meet the high standards required, every floor must be polished, every bed made and all the sailors perfectly turned out. But all this hard work has its rewards. If the ship passes the test, the crew members will be allowed three nights in Malta. “If you give me the enthusiasm you’ve shown over the last few weeks,” says Commander Tim Johnson, “we’ll breeze through it.”

As the day of the inspection arrives, a Flag Officer Sea Training (FOST) team comes aboard via helicopter. The team is led by Rear Admiral Richard Ibbotson, who will have the final say as to whether Illustrious’s crew will pass the test. “They’ve got to get past me first,” he says, ominously.

The inspection begins with a realistic emergency test, including a mock-up fire in the hangar complete with smoke and pretend casualties. The FOST team then adds another scenario into the mix – a stricken ship in the water nearby must be rescued and towed to safety. After a hectic day, the ship’s company gathers in the hangar to hear the results of the inspection. Will it be good news, or will the crew fail once more, meaning yet another costly delay to the deployment?

A tense few minutes later and Captain Steve Chick delivers the news for which everybody has been hoping – the crew has passed! Now, Illustrious can finally leave British waters for Malta, where the sailors can take a well-earned break. Before they arrive, however, there is the dangerous Strait of Gibraltar to negotiate, where the ship is at risk from terrorists and smugglers. If anything is to happen on the way to Malta, it will happen in this narrow channel, so the sailors must arm themselves and prepare for battle.