The west of Ireland is one of the most spectacularly beautiful coastlines in the world and for one glorious summer it's home from home for Monty Halls and his over enthusiastic dog Reuben. Some of the biggest and most mysterious animals on the planet migrate through the waters off Connemara but nobody knows how many whales, dolphins, porpoises, basking sharks and even blue sharks are out there. It's Monty's job to find out before the winter storms bring research to an end. Monty is back to his roots as a marine biologist, living on an island near the fishing village of Roundstone and trying to feed himself from the sea and what he can grow in his cottage garden. The sea teems with life and Monty is soon enjoying dolphin, seal and otter encounters plus a spectacular dive with huge conger eels. But there's a darker side to the job. More than a hundred whales and dolphins strand on Irish shores every year and Monty is called to reports of a young minke whale that's been washed up on rocks. It's too late to save the whale, but it's a valuable opportunity to learn as much as he can about how it lived and died.

This time his mission is to track down basking sharks, true monsters of the deep which can grow up to 30 feet long. They appear off our shores every summer but we know remarkably little about these gentle giants and Monty is on constant lookout for their telltale fins. He is determined to tag as many as he can in the hope that scientists can eventually discover their migration routes. Back on shore, his attempts at self-sufficiency are sabotaged by otters, who've learnt to raid lobster creels,and his faithful dog Reuben,who accidentally savages him on a winkle-picking expedition.

This time his mission is to track dolphins in the bay using sonar technology to record the whistles and clicks they use to communicate with each other. He also visits Inishturk, one of Ireland's most remote inhabited islands, to recruit the seven pupils of the island school as whale and dolphin watchers; has a magical underwater encounter with seals and throws his first party for the locals.

Monty goes shark fishing and reels in a couple of blue sharks that have crossed the Atlantic as part of their annual migration. It takes strong nerves and quick reactions to avoid getting bitten as tags are attached to the sharks' dorsal fins before they are released. Monty is also called out to investigate reports that a dolphin is attacking swimmers.

Monty goes on a whale watching mission with the Irish Air Corps, is called out in the middle of the night to search for a stranded basking shark and survives a close shave racing traditional sailing boats.

Storms are making it difficult to put to sea, but Monty must retrieve an acoustic listening device he anchored on the sea bed to monitor whale and dolphin movements in his bay. But that was four months ago and now there is no sign of the 4000 euro recorder. Without the data it has recorded, much of Monty's six months work will have been wasted.