For four centuries, the border line running from La Cure to Boncourt split two worlds. Two slopes of the same mountain lived divergent destinies — different rulers, different wealth, different gods — while sharing forests, families, recipes and secrets. The stones planted along the line since the 1550s still tell the official story in coats of arms; the huts with Paris-station names tell it in whispered messages. But the deepest story is a human one: smugglers crossing with absinthe, watches and cattle by night to make a living — and, when wars drove refugees to the line, ordinary people who carried them across at their own risk. Our outings read this border on foot: its markers and its smugglers, its refugees and its rescuers, its absinthe and its escape games.