To plan secretly with other people to do something bad, illegal, or against someone’s wishes. (Cambridge Dictionary)
If two or more people or groups conspire to do something illegal or harmful, they make a secret agreement to do it. (Collins Dictionary)
If events conspire to produce a particular result, they seem to work together to cause this result. (Collins Dictionary)
To join in a secret agreement to do an unlawful or wrongful act or an act which becomes unlawful as a result of the secret agreement. (Merriam – Webster)
To act in harmony toward a common end. (Merriam – Webster)
Make secret plans jointly to commit an unlawful or harmful act. (Oxford Dictionaries)
Of events or circumstances) seem to be working together to bring about a particular negative result. (Oxford Dictionaries)
Paulo Coelho: How to Get the Universe to Conspire in Your Favour.