A cannabis farm worth £45,000 was discovered by police in two adjoining Hartlepool homes.
Two neighbouring properties were searched on Chester Road this morning, after members of the public contacted police to raise their concerns.
The set up shows one property with an estimated 100 plants inside, and the potential for more plants to grow.
It is believed that the property next door was housing those responsible for growing the plants, and a hole had been made in a wall to adjoin the properties.
There was also a significant fire risk at the addresses, as the electricity meter had been bypassed.
A man has been arrested on suspicion of production of a controlled drug. He remains in police custody.
Anyone with information regarding drugs activity in their area is asked to contact Cleveland Police on 101 or the Community Drugs Enforcement Team confidential drugs line on 0800 0929 702.