niagara niagara ( r ) * * * ( out of * * * * ) bob gosse's niagara niagara follows a blueprint not unlike a lot of young-lovers-on-the-road movies . wild marcy ( robin tunney ) and calm seth ( henry thomas ) meet cute , literally running into each other while shoplifting at a local store . a mere couple of scenes later , the two embark on a journey to toronto from their small , unnamed american town in pursuit of a rare doll that marcy desperately wants . along the way , true love inevitably blossoms . what sets niagara niagara apart , though , is that marcy is afflicted with tourette's syndrome , a neurological disorder that causes sudden muscle and vocal tics . tunney , displaying an acting range not hinted at in the teenage witch thriller the craft , delivers an astonishing performance that won her the best actress prize at last year's venice film festival . to term her work a tour-de-force is not to imply that she attacks the scenery ; tunney's effectiveness lies in her modulation and vulnerability , which makes her depiction of marcy's illness--which often causes her to act violently--that much more convincing and tragic . she and the nicely subtle thomas develop a sweetly innocent and beguilingly off-kilter chemistry . their journey hits a few rough spots creatively along the way , mostly the fault of writer matthew weiss . a detour involving a kindly widower ( michael parks ) who takes the couple in brings the story to a screeching halt , and the key character of a trigger-happy pharmacist ( stephen lang ) is highly unbelievable . but these missteps do not blunt the power of tunney's bravura turn , which carries niagara niagara to a level of poignance it would not have otherwise achieved . ( opens march 20 ) 
