Bennie Barrier returns in another big city adventure. Mrs Fry decides to treat everyone to her legendary homemade mushroom soup but by dawn the next day, the maintenance yard is a war zone of groaning cones and barriers. When Bennie Barrier notices something off about the mushrooms; tiny blue flecks that were not part of Mrs Fry's usual recipe, he becomes convinced that this is no innocent tummy bug but a strike to take his team away from the city centre whilst a bigger heist unfolds. As the team staggers through the investigation battling waves of sickness and increasingly desperate toilet stops, Bennie begins to wonder how far Carlton Cone is really willing to go for revenge over the team that sent him away.