Having hired Eric Catchpole as an apprentice, Lovejoy sets out to unravel the meaning of a Japanese firefly cage.As Lovejoy and Eric are in hot pursuit (on Eric's motorbike) of a lovely lady with something they want, they hit a pool of water in the road and give a drenching to Jane (Lady Felsham), who is busy unveiling a plaque. When, later, Lovejoy rings the doorbell at Felsham Hall, complex chemistry begins, and Jane is soon showing Lovejoy around her attic...

Tinker and Eric take a break at Eric's Uncle Jack's pub. Meanwhile, Lovejoy is asked to show a visiting couple around the antiques shops. Trouble is, he also has a very large Welsh Dresser to get rid of. Eric decides to stay on and run the pub.

A rare Celtic cross is stolen from Charlotte's aution house, after Lovejoy asked the porter to let a friend look at it. Charlotte and Lovejoy set out on the thief's trail and find themselves on a treasure hunt in the west of Wales. But they are not the only ones after the cross.Charlotte turns down Lovejoy's invitation to share a bedroom at a village inn.