As Sasha is forced to work alongside her ex-husband when he fills in for Strickland, Gerry returns to his roots in Bermondsey for his youngest daughter's wedding. As a consequence, he is thrown into a case involving the possible murder of an architecture student who is also the grandson of an old friend who has just been released from prison. Back at UCOS, Dan puts the body language skills he has learnt on an FBI course to the test.