List of New Tricks Episodes - Series 4 (2007)

Sandra manages to prevent Jack from taking revenge against Ricky Hanson, but in the process causes the whole team to end up in hospital. Whilst at the hospital, a case in which three patients died on the same night after lethal overdoses of drugs comes to light, and Jack has a further encounter with Ricky Hanson – who tries to kill him – but is luckily subdued by Brian. Meanwhile, Strickland places a temporary team member, DCI Karen Hardwick, in the UCOS office, in an attempt to discover what was behind the team's hospitalisation.

Sandra’s mother, Grace, falls ill with Ménière's disease and has to find an assisted living home. While visiting a higher-end facility, called Whitemead, a suspicious death, which occurred a year earlier, comes to light via one Leonard Casey, a patient who was befriended with the deceased mentioned. When Strickland refuses permission to investigate, the team decides to look into the incident on their own anyway. They decide to go undercover with Jack as a new patient, Gerry as his son and Brian as his docter, being a so-called reiki psychatrist, in order to discover just how elderly patient Maggie Newley died. While inside, Jack discovers a jealous resident, Pru Saunders, the manager and his daughter who are stealing valuables, and the wife of the son of the departed, who seems to have less than excited emotions about the team's ongoing investigation.

When an armoured security van is found dumped at the bottom of the lake, the team investigates a 17-year-old murder case, in which Marie Sinclair, the wife of known criminal Andrew Sinclair, who owned the security company at the time, was found dead, and the suspected killer, Michael Dudley, disappeared. Meanwhile, Gerry is offered a part-time overnight job to earn himself some extra cash – but unknown to him, his employer and the successor of Andrew Sinclair, called Steve Palmer, is the man the team are looking for in their case. When suddenly the body of the suspected killer is found in the same lake, the team uncover a jewellery scam that resulted in the death of two innocent people.

When Jack goes to amend his will, he stumbles upon a case in which a man is contesting his aunt's will after she is found to have left all of her worldly goods to her horde of cats, but the elderly woman herself, who died rich and lonely and was called Dorothy Hepple, died in suspicious circumstances some ten years ago. Upon delving deeper into the case, he manages to discover a web of cheats, liars and relatives who will seem to do anything to get their hands on her money: her nephew, Harry Hepple, and niece, Caroline Baker, with the latter's husband, Peter Baker, and her caretaker, Dale Hewson. Moreover, her neighbour, Tim Cuswell, wasn't very fond of her at all: he even loathed her, and especially her bunch of cats, being the proud owner of a dog.

The team reinvestigates the 1950s murder of Fred(erick) Tully, a wages clerk at Battersea Power Station. The case is reinvestigated when Hannah Parker, the granddaughter of the man originally hanged for the murder, Richard Dunne, proclaims his innocence, and blames his hanging on police corruption and/or incompetence.

After, Scampi, Brian’s dog, discovers the skeletal remains of a body in a wood, one Jackie Small confesses to the murder of Tina Murphy and one Andrew Bartlett begins to ask suspicious questions about the body, leading the team to tag him as a suspect.

The murder of a photographer in 1987 is reopened when a camera and film belonging to him are discovered.

The team investigates a case of spontaneous combustion resulting in the death of a circus owner and ringmaster. Meanwhile Sandra struggles with a discovery about her father, which the rest of the team had kept from her.