The brothers DeWit continue their insurance fraud thesis investigation with another sister, nurse Veerle, but leave none the wiser. Yet she too had a motive since Jean-Claude discovered her adultery and threatened to inform her unsuspecting husband, paramedic Wout. She sanctimoniously refused to join the failed arsonist sisters' next plan, poisoning, but eagerly advises against mushrooms, coming up with a non-suspicious hospital drug. Yet the attempt on Jean-Claude's life on his monthly liver dinner day fails when the dog eats what no human house-mate ever touches.

The brothers continue their investigation by questioning youngest sister (Re)Bekka, who obviously lies and realizes only now that she hasn't been dating an undertaker but Mathias. She joined the murder sorority after Jean-Claude objected to a flippant promise by his wife to grant Becca a private loan for her business project, which has already been notarized although nobody even consulted him. Their next murder attempt, electrocution in bath, went wrong due to childish Becca and accidentally killed an old neighbor, Alfons. After a prank war got out of hand, ...

The bothers move on, questioning even more hostile, one-eyed sister Birgit. She remembered how Jean-Claude's mean hatred for his daughter's kitten, which he ended up killing semi-accidentally, motivated a new attempt on his life; The sisters, who felt little guilt for their failed electrocution ending sickly senior neighbor Fons's life, decide on replacing the usual quiet annual family outing with a paint-ball initiation. Birgit practiced to become deadly accurate with frozen ammunition, but Jean-Claude's helmet number six gets mixed up with an innocent friendly ...

Thomas Dewitt finally obtains the autopsy, which strengthens his murder suspicion. Brother Mathias however almost prefers to believe in an accident, for his lover's sake. A few months earlier, Jean-Claude Delcorps succeeded in eliminating Eva as rival for a promotion and made another attempt to inform nurse Wouter Cox of his wife's adultery. The sisters planned another murder attempt, using a rape drug to stage a hanging, but the garage rod he's suspended on bent and triggered the door opening mechanism, so neighbor Valère Bols saved his life.

Thomas confronts Veerle with a surprising new lead: why did her family hire a private detective during the previous summer? The sisters enlist the services of a hit-man to take care of the dirty work.

Having hit a dead end, the Dewitt brothers turn their attention to Jean-Claude's parents, only to learn both are missing in action. Having been tricked by Jean-Claude into thinking their boss Gerard is gay, Frederik makes amorous advances towards his superior. Goedele decides to get out more after her daughter Bloeme claims her life is boring and uneventful, but this proves trickier than she first thought.

The sisters call an urgent meeting: the Dewitts are closing in and Bekka's relationship with Mathias has become a liability. Bekka faces a shocking revelation after tailing Jean-Claude to a graveyard.

Their mission is accomplished but the sisters can't rest on their laurels as they feel the Dewitts breathing down their necks. If they can't prove Jean-Claude was murdered, the brothers may face jail.