Martin is in his early thirties but looks like an eternal teenager. His grandfather, with whom he spends all his weekends and holidays, has just died. This year, he finds himself alone on the West French coast. His time is devoted entirely to shore fishing, an activity he has been practicing from a young age. Martin thrives in this little game of hide and seek with nature, a simple and playful pleasure that calms and reassures him. But to the rhythm of the tides, Martin lets himself be guided by his dark passenger towards increasingly strange behavior and rituals.