Non-custodial parent runs out of state w/child. How can custodial parent get child back?

A Non-custodial parent (mother) took her 3 yr old child from MI to NJ in the middle of the night while on "parenting time". She has no intention on returning child to resident state or custodial parent and insists "she'll" work something out with custodial parent so he can visit!
She disregarded the 100 mile rule as set forth on custody paperwork and now custodial parent is in a quagmire of red tape because the other state does not seem to recognize nor care about his custodial rights . What can be done? - Is this your question? Add additional information