Out of nowhere, former District Attorney, Samantha Simms (Meredith Monroe - Beyond the Prairie, Part 2) receives a call from her ex, Brad (Rick Ravanello - Doomsday Prophecy), in Seattle as her sister, Brenda (Nicole LaPlaca - Another Cinderella Story), has been arrested for murder. Dropping everything and jumping on the first plane to Seattle, Samantha takes it upon herself to represent her sister and discovers that the dead man was not only a married man who was having an affair with Brenda but he was killed in a hit and run involving Brenda's car which she reported missing the day after the incident. With past issues causing tension between Samantha and Brenda and Brenda hiding something the odds are stacked against Samantha clearing her sister.
Strip away the names and the location and what you have left with "Secret Liaison" is a stereotypical made for TV thriller where a woman investigates a case to try and clear a friends name only to put herself in danger doing so. Yes this time the friend happens to be the sister but that only means we can add another cliche to the mix which is some past family issues causing difficulties. Plus we have another cliche tossed in there because Samantha comes face to face with her ex, Brad, the detective who is more than happy to assist as he obviously still cares for her. Trust me with this much cliche going on that "Secret Liaison" would need a miracle to end up anything more than average and by the book.
Unfortunately there are no miracles to save "Secret Liaison" as it features a routine bunch of characters who are forgettable, played by a cast who in some cases I feel may have been cast as much for their looks as their acting ability. Not that anyone is really terrible when it comes to the acting in "Secret Liaison" as it is at the level which you expect from this sort of made for TV movie but it does mean that no one in the cast stands out for the right reasons.
What this all boils down to is that "Secret Liaison" is nothing more than a typical made for TV thriller which involves a woman investigating a crime, getting in to danger and dealing with not only her feelings for a helpful ex but also old family issues.