Crime fun on the coast. In Fredenbüll, there is an uproar: several wind turbines are being installed on the dike foreland, prompting the local environmentalists to take action. Even Grandma Ahlbeck supports the hastily founded initiative "Sei (k)ein Frosch e.V.", which is concerned about the endangered red-bellied toad. One morning, a dead body is found in the still damp concrete base of one of the wind turbines! Is the mysterious unknown person, who is guarded by men in dark suits, involved? "That's the BKA," says Police Chief Thies Detlefsen, immediately sensing a major case.