A body dredged up from a canal is tentatively identified as the son of a British MP, but when she views the body she says it is not her son. Van der Valk refuses to believe this and calls on his British colleagues to help prove the boy's identity. The boy's face is well known in Amsterdam's transvestite and transexual scene and van der Valk's inquiries there lead him deeper and deeper into a dark world of sexual depravity and exploitation involving some of the most prominent public figures in Europe. Samson of course desperately advises him to proceed with extreme caution. In the face of the mother's refusal to co-operate van der Valk finds his best hope is to look elsewhere in the family for help.