Lovejoy travels to Venice to investigate the murder of a friend. The dead friend had bought a painting Lovejoy believed was a fake. In Venice, he is drawn into an ambitious art swindle, and identical twins Caterina and Lavinia are behind the scam.

In Venice, Lovejoy gets a job working for Caterina and Lavinia, with a view to busting their scam, and meets a Scottish forger called 'Lucky' Luciano. Lovejoy and Lucky together unravel the mystery of the Island of Rats.

As the third series begins, Lovejoy returns to Felsham after a long break in Spain, where he was trying (without marked success) to learn to paint. He quickly seeks out Tinker (who has joined a monastery), Jane, who has a new look, and Eric, now working as a security guard. Victoria Cavero, an old friend of Jane's, comes to stay, and Lovejoy loses no time in falling for her. Victoria wants to sell a South American gold ring, and the ring sets in motion strange events for Lovejoy and Jane, including safecracking, kidnapping, polo and betrayal.

Lovejoy is spending more and more time with Victoria, not so much on his business. Together with Jane and Alexander, he and Victoria go away for the weekend at a friend's cottage. Meanwhile, Lovejoy buys some drawings for a song and sells them to an art gallery for a good profit. He is shaken when the pictures are denounced as fakes - even the artist says they are not his, but Lovejoy is sure they are. What is going on?