Following a welcome break in Cyprus, HMS Queen Elizabeth heads back to sea, but after passing through the Suez Canal it's discovered that one sailor has contracted Covid-19 while on shore leave. A week later, as the ship enters the Indian Ocean, the vurus has spread almost out of control with 400 sailors now in isolation - either because they are infected or are close contacts with those who have tested positive. With almost a third of the ship's labour force out of commission, command has to find ways of keeping the aircraft carrier operational