Bellrock cove is a busy seaside resort at the mouth of the River Shannon. It's also home to an Elite Coastguard Special Operations unit. Primarily their job is search and rescue, but a busy waterway brings many challenges and smuggling is one that regularly puts their detection skills to the test. Prior to a major boating event, a quantity of heroin is found at a quiet beach north of the town which leads to a series of shootouts and chases on both land and sea. A farmer is also found dead under suspicious circumstances. Could there be a connection? Just to complicate things further and heap more pressure on the now overstretched unit, a light aircraft sends out a May-day call as the boating event is underway.