 Worried about her mother s latest health problem, the pancreas, Jeanne asks Billy to explain medically. Jef and the students help Odilon rehearse the part of Dingemans the Strangler for the annual play in jail, a hopeless task for them and painful for him as the result of various misunderstandings and Sam s self-defense lessons to Betty. Billy is furious that his latest conquest Agnes learned what a party animal and lady killer he is from from fellow economics student Charles-Victor, so he seeks a sneaky revenge using Joop, a Dutch friend, to lure him to Amsterdam.