We provide a function try so that the pattern: (try (lambda (p) x) (lambda (e) y)) performs the code x and if x should call p, then perform code y without return from p. The parameter e, for y, is bound to the value passed to p by x. try returns whatever x or y returns. The continuation created by any call to p is discarded; p does not return. 
(define (try pb pe) (call/cc (lambda (p) (pb (lambda (ev) (p (pe ev)))))))

(define exc (lambda (t) (write (list "exception" t)) 'e))
(define work (lambda (e) (write "working") 'w))
(define worke (lambda (e) (write "attempting") (e "peculiar") (write "don't get here!")))

(try work exc) ; => "working"w
(try worke exc) ; => "attempting"("exception" "peculiar")e
(call/cc (lambda (e) 42)) yields 42, but the spec is not clear on this. For small step semantics you could say that proc (argument to call/cc) is invoked with the same continuation as argument and continuation. That is to say that the current continuation becomes the continuation of the new activation record, and also the value of the argument. In big step semantics you could say that call/cc returns what ever the proc returns and on different occasions what ever argument is passed to the argument to the proc.