It is a sunny day in April.  There are no clients, so Watson persuades Holmes to take a gentle stroll through Hyde Park.  They encounter a party of schoolboys stripping off to swim in the Serpentine.  Whilst the boys crowd around Holmes for autographs Mr. Henderson, the schoolmaster, makes a pass at Watson.  Being an ex-army chap he is offended by the invitation.  On the way back Holmes tries to broaden his companion’s bigoted outlook, but to no avail.  Mr. Munro awaits them in Baker Street – he is mystified by his wife visiting a local cottage and suspects her of having an affair.  Worse still, the cottage seems to occupied by a demon with a yellow face, which evokes childhood nightmares for Watson.  A guerilla raid on the property by Holmes and Watson results in a shocking outcome for their client and a life-changing moment for the Doctor.  That evening, Holmes and Watson invite Mr. Henderson to attend an am-dram production of Dick Whittington starring Mrs Hudson.  When Watson sneaks off to roger Holmes’s sister, Rachel, he thinks that he is heading to sensual heaven, but in fact he is descending to blackmail hell.